diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 0000000..255603e
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,5 @@
+[build]
+rustflags = ["-C", "target-feature=+simd128"]
+
+[unstable]
+build-std = ["panic_abort", "std"]
diff --git a/.github/workflows/prepare-release.yml b/.github/workflows/prepare-release.yml
new file mode 100644
index 0000000..5f53029
--- /dev/null
+++ b/.github/workflows/prepare-release.yml
@@ -0,0 +1,65 @@
+name: Prepare release
+
+on:
+  workflow_dispatch:
+    inputs:
+      releaseType:
+        description: 'Type of release'
+        required: true
+        default: 'patch'
+        type: choice
+        options:
+          - major
+          - minor
+          - patch
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}-root
+  cancel-in-progress: true
+
+jobs:
+  prepare_release:
+    runs-on: ubuntu-latest
+
+    outputs:
+      ref: ${{ steps.push-tag.outputs.commit_long_sha }}
+
+    steps:
+      - name: Generate a token
+        id: generate-token
+        uses: actions/create-github-app-token@v1
+        with:
+          app-id: ${{ secrets.PUSH_O_MATIC_APP_ID }}
+          private-key: ${{ secrets.PUSH_O_MATIC_APP_KEY }}
+
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          token: ${{ steps.generate-token.outputs.token }}
+
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+
+      - run: cargo install cargo-edit
+
+      - name: Bump version
+        run: cargo set-version --bump "${{ inputs.releaseType }}"
+
+      - name: Get version
+        run: echo "IMMICH_VERSION=$(cargo metadata --format-version 1 --no-deps | jq -r '.packages.[0].version')" >> $GITHUB_ENV
+
+      - name: Commit and tag
+        id: push-tag
+        uses: EndBug/add-and-commit@v9
+        with:
+          default_author: github_actions
+          message: 'chore: version ${{ env.IMMICH_VERSION }}'
+          tag: ${{ env.IMMICH_VERSION }}
+          push: true
+
+      - name: Create draft release
+        uses: softprops/action-gh-release@v2
+        with:
+          draft: true
+          tag_name: ${{ env.IMMICH_VERSION }}
+          token: ${{ steps.generate-token.outputs.token }}
+          generate_release_notes: true
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
new file mode 100644
index 0000000..a9e9fb8
--- /dev/null
+++ b/.github/workflows/publish.yml
@@ -0,0 +1,40 @@
+name: Publish
+
+on:
+  workflow_dispatch:
+  release:
+    types: [published]
+
+permissions:
+  packages: write
+
+jobs:
+  publish:
+    name: Publish
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      # This sets up .npmrc to use NODE_AUTH_TOKEN below
+      # See https://github.com/actions/setup-node/blob/48b90677b6048efbc723b11a94acb950d3f1ac36/src/authutil.ts#L48
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 'lts/*'
+          registry-url: 'https://registry.npmjs.org'
+
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+
+      - uses: jetli/wasm-pack-action@v0.4.0
+        with:
+          version: v0.13.1
+
+      - name: Build
+        run: npm run build
+
+      - name: Publish
+        run: npm publish
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..6045409
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,28 @@
+name: Test
+on:
+  workflow_dispatch:
+  pull_request:
+  push:
+    branches: [main]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+      - uses: browser-actions/setup-firefox@v1
+
+      - uses: jetli/wasm-pack-action@v0.4.0
+        with:
+          version: v0.13.1
+
+      - name: Test
+        run: wasm-pack test --firefox --headless
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f76a348
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+target
+node_modules
+*.ll
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..56a409e
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,314 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "bumpalo"
+version = "3.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "79296716171880943b8470b5f8d03aa55eb2e645a4874bdbb28adb49162e012c"
+
+[[package]]
+name = "cc"
+version = "1.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a012a0df96dd6d06ba9a1b29d6402d1a5d77c6befd2566afdc26e10603dc93d7"
+dependencies = [
+ "shlex",
+]
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "js-sys"
+version = "0.3.76"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6717b6b5b077764fb5966237269cb3c64edddde4b14ce42647430a78ced9e7b7"
+dependencies = [
+ "once_cell",
+ "wasm-bindgen",
+]
+
+[[package]]
+name = "justified_layout"
+version = "0.1.0"
+dependencies = [
+ "wasm-bindgen",
+ "wasm-bindgen-test",
+]
+
+[[package]]
+name = "log"
+version = "0.4.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7a70ba024b9dc04c27ea2f0c0548feb474ec5c54bba33a7f72f873a39d07b24"
+
+[[package]]
+name = "minicov"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f27fe9f1cc3c22e1687f9446c2083c4c5fc7f0bcf1c7a86bdbded14985895b4b"
+dependencies = [
+ "cc",
+ "walkdir",
+]
+
+[[package]]
+name = "once_cell"
+version = "1.20.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
+
+[[package]]
+name = "proc-macro2"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37d3544b3f2748c54e147655edb5025752e2303145b5aefb3c3ea2c78b973bb0"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0e4dccaaaf89514f546c693ddc140f729f958c247918a13380cccc6078391acc"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "same-file"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93fc1dc3aaa9bfed95e02e6eadabb4baf7e3078b0bd1b4d7b6b0b68378900502"
+dependencies = [
+ "winapi-util",
+]
+
+[[package]]
+name = "scoped-tls"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e1cf6437eb19a8f4a6cc0f7dca544973b0b78843adbfeb3683d1a94a0024a294"
+
+[[package]]
+name = "shlex"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
+
+[[package]]
+name = "syn"
+version = "2.0.95"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46f71c0377baf4ef1cc3e3402ded576dccc315800fbc62dfc7fe04b009773b4a"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "adb9e6ca4f869e1180728b7950e35922a7fc6397f7b641499e8f3ef06e50dc83"
+
+[[package]]
+name = "walkdir"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "29790946404f91d9c5d06f9874efddea1dc06c5efe94541a7d6863108e3a5e4b"
+dependencies = [
+ "same-file",
+ "winapi-util",
+]
+
+[[package]]
+name = "wasm-bindgen"
+version = "0.2.99"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a474f6281d1d70c17ae7aa6a613c87fce69a127e2624002df63dcb39d6cf6396"
+dependencies = [
+ "cfg-if",
+ "once_cell",
+ "wasm-bindgen-macro",
+]
+
+[[package]]
+name = "wasm-bindgen-backend"
+version = "0.2.99"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5f89bb38646b4f81674e8f5c3fb81b562be1fd936d84320f3264486418519c79"
+dependencies = [
+ "bumpalo",
+ "log",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-futures"
+version = "0.4.49"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38176d9b44ea84e9184eff0bc34cc167ed044f816accfe5922e54d84cf48eca2"
+dependencies = [
+ "cfg-if",
+ "js-sys",
+ "once_cell",
+ "wasm-bindgen",
+ "web-sys",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.99"
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+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-backend",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.99"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "943aab3fdaaa029a6e0271b35ea10b72b943135afe9bffca82384098ad0e06a6"
+
+[[package]]
+name = "wasm-bindgen-test"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c61d44563646eb934577f2772656c7ad5e9c90fac78aa8013d776fcdaf24625d"
+dependencies = [
+ "js-sys",
+ "minicov",
+ "scoped-tls",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "wasm-bindgen-test-macro",
+]
+
+[[package]]
+name = "wasm-bindgen-test-macro"
+version = "0.3.49"
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "web-sys"
+version = "0.3.76"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "04dd7223427d52553d3702c004d3b2fe07c148165faa56313cb00211e31c12bc"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
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+ "windows-sys",
+]
+
+[[package]]
+name = "windows-sys"
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+ "windows-targets",
+]
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+[[package]]
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+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.52.6"
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+
+[[package]]
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+
+[[package]]
+name = "windows_i686_gnu"
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+
+[[package]]
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+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.6"
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+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.6"
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+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.6"
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diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..7ab6276
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,23 @@
+[package]
+name = "justified_layout"
+version = "0.1.0"
+edition = "2021"
+license = "AGPL-3"
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+wasm-bindgen = "0.2"
+
+[dev-dependencies]
+wasm-bindgen-test = "0.3.0"
+
+[profile.release]
+lto = true
+codegen-units = 1
+strip = true
+panic = "abort"
+
+[package.metadata.wasm-pack.profile.release]
+wasm-opt = ["--enable-simd", "--fast-math", "--gufa", "-O3", "--type-finalizing"]
diff --git a/js/index.ts b/js/index.ts
new file mode 100644
index 0000000..64c7269
--- /dev/null
+++ b/js/index.ts
@@ -0,0 +1,54 @@
+import { get_justified_layout } from '../pkg/justified-layout-wasm.js';
+
+export interface LayoutOptions {
+  rowHeight: number;
+  rowWidth: number;
+  spacing: number;
+  heightTolerance: number;
+}
+
+/*
+ * This is a wrapper class to interact with the layout generated by the Wasm function.
+ * This design is used because:
+ *   - The layout is stored in a Int32Array for efficiency, which is not very user-friendly
+ *   - Creating objects from the Int32Array takes more time than the actual layout calculation
+ *   - Using getter methods avoids dynamic heap allocation beyond the initial layout calculation
+ *   - The class provides a static prototype that can be JIT-compiled efficiently, inlining all of its methods
+ *   - V8 does not box int32 values, unlike most other data types
+ *   - Moving floats from Wasm to JS is expensive, probably due to validation around NaN and Infinity
+ */
+export class JustifiedLayout {
+  layout: Int32Array;
+
+  constructor(aspectRatios: Float32Array, { rowHeight, rowWidth, spacing, heightTolerance }: LayoutOptions) {
+    if (aspectRatios.length === 0) {
+      this.layout = Int32Array.of(0, 0, 0, 0);
+    } else {
+      this.layout = get_justified_layout(aspectRatios, rowHeight, rowWidth, spacing, heightTolerance);
+    }
+  }
+
+  get containerWidth() {
+    return this.layout[0];
+  }
+
+  get containerHeight() {
+    return this.layout[1];
+  }
+
+  getTop(boxIdx: number) {
+    return this.layout[boxIdx * 4 + 4]; // the first 4 elements are containerWidth, containerHeight, padding, padding
+  }
+
+  getLeft(boxIdx: number) {
+    return this.layout[boxIdx * 4 + 5];
+  }
+
+  getWidth(boxIdx: number) {
+    return this.layout[boxIdx * 4 + 6];
+  }
+
+  getHeight(boxIdx: number) {
+    return this.layout[boxIdx * 4 + 7];
+  }
+}
diff --git a/package-lock.json b/package-lock.json
new file mode 100644
index 0000000..5730ee9
--- /dev/null
+++ b/package-lock.json
@@ -0,0 +1,13 @@
+{
+  "name": "justified-layout-wasm",
+  "version": "0.1.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "justified-layout-wasm",
+      "version": "0.1.0",
+      "license": "AGPL-3"
+    }
+  }
+}
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..4468026
--- /dev/null
+++ b/package.json
@@ -0,0 +1,18 @@
+{
+  "name": "@immich/justified-layout-wasm",
+  "type": "module",
+  "version": "0.0.0",
+  "license": "AGPL-3",
+  "scripts": {
+    "build": "wasm-pack build --no-pack --out-name justified-layout-wasm"
+  },
+  "files": [
+    "pkg/justified-layout-wasm.js",
+    "pkg/justified-layout-wasm_bg.js",
+    "pkg/justified-layout-wasm_bg.wasm"
+  ],
+  "main": "js/index.ts",
+  "sideEffects": [
+    "pkg/justified-layout-wasm.js"
+  ]
+}
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
new file mode 100644
index 0000000..f70d225
--- /dev/null
+++ b/rust-toolchain.toml
@@ -0,0 +1,3 @@
+[toolchain]
+channel = "nightly"
+components = ["rust-src"]
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..6e0e4d8
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,127 @@
+#![feature(slice_as_chunks)]
+
+use wasm_bindgen::prelude::*;
+
+pub struct LayoutOptions {
+    pub row_height: f32,
+    pub row_width: f32,
+    pub spacing: f32,
+    pub tolerance: f32,
+}
+
+/// Given an input of aspect ratios representing boxes, returns a vector 4 times its length + 4.
+/// The first element is the maximum width across all rows, the second is the total height required
+/// to display all rows, the next two are padding, and the remaining elements are sequences of 4 
+/// elements for each box, representing the top, left, width and height positions.
+/// `row_height` is a positive float that is the target height of the row.
+///     It is not strictly followed; the actual height may be off by one due to truncation, and may be
+///     substantially different if only one box can fit on a row and this box cannot fit with the
+///     target height. The height cannot exceed this target unless `tolerance` is greater than zero.
+/// `row_width` is a positive float that is the target width of the row.
+///     It will not be exceeded, but a row may have a shorter width if the boxes cannot fill the row
+///     width given the `tolerance`.
+/// `spacing` is a non-negative float that controls the spacing between boxes, including between rows.
+///     Notably, there is no offset applied in directions where there is no box.
+///     The first box will have its top and left positions both at 0, not at `spacing`, and so on.
+/// `tolerance` is a non-negative float that gives more freedom to fill the row width.
+///     When there is free space in the row and the next box cannot fit in this row, it can scale
+///     the boxes to a larger height to fill this space while respecting aspect ratios. A value of
+///     0.15 signifies that the actual row height may be up to 15% greater than the target height.
+///
+/// Note: The response being Vec<i32> rather than a struct or list of structs is important, as the
+///       JS-WASM interop is *massively* slower when moving structs to JS instead of an array and
+///       importing integers is faster than floats.
+#[wasm_bindgen]
+pub fn get_justified_layout(
+    aspect_ratios: &[f32],
+    row_height: f32,
+    row_width: f32,
+    spacing: f32,
+    tolerance: f32,
+) -> Vec<i32> {
+    let options = LayoutOptions {
+        row_height,
+        row_width,
+        spacing,
+        tolerance,
+    };
+
+    _get_justified_layout(aspect_ratios, options)
+}
+
+#[inline(always)]
+fn _get_justified_layout(aspect_ratios: &[f32], options: LayoutOptions) -> Vec<i32> {
+    let mut positions = vec![0.0; aspect_ratios.len() * 4 + 4]; // 2 for container width and height, 2 for alignment
+    let max_row_height = options.row_height * (1.0 + options.tolerance);
+    let mut cur_row_width = 0.0;
+    let mut max_actual_row_width = 0.0;
+    let mut row_start_idx: usize = 0;
+    let mut top = 0.0;
+
+    for (i, aspect_ratio) in aspect_ratios.iter().enumerate() {
+        let box_width = aspect_ratio * options.row_height;
+        cur_row_width += box_width;
+
+        // there are no more boxes that can fit in this row
+        if cur_row_width > options.row_width && i > 0 {
+            let row = &mut positions[row_start_idx * 4 + 4..i * 4 + 4];
+            let aspect_ratio_row = &aspect_ratios[row_start_idx..i];
+
+            // treat the row's boxes as a single entity and scale them to fit the row width
+            let total_aspect_ratio: f32 = aspect_ratio_row.iter().sum();
+            let spacing_pixels = options.spacing * f32::from(aspect_ratio_row.len() as u16 - 1);
+            let scaled_row_height =
+                ((options.row_width - spacing_pixels) / total_aspect_ratio).min(max_row_height);
+
+            let mut actual_row_width = spacing_pixels;
+            let mut left = 0.0;
+            // SAFETY: this slice's length is guaranteed to be a multiple of 4
+            let row_positions = unsafe { row.as_chunks_unchecked_mut::<4>() };
+            for i in 0..aspect_ratio_row.len() {
+                let pos = &mut row_positions[i];
+                let width = aspect_ratio_row[i] * scaled_row_height;
+                pos[0] = top;
+                pos[1] = left;
+                pos[2] = width;
+                pos[3] = scaled_row_height;
+                left += width + options.spacing;
+                actual_row_width += width;
+            }
+            top += scaled_row_height + options.spacing;
+            max_actual_row_width = actual_row_width.max(max_actual_row_width);
+            row_start_idx = i;
+            cur_row_width = box_width;
+        }
+        cur_row_width += options.spacing;
+    }
+
+    // this is the same as in the for loop and processes the last row
+    // inlined because it ends up producing much better assembly
+    let row = &mut positions[row_start_idx * 4 + 4..];
+    let aspect_ratio_row = &aspect_ratios[row_start_idx..];
+    let total_aspect_ratio: f32 = aspect_ratio_row.iter().sum();
+    let spacing_pixels = options.spacing * f32::from(aspect_ratio_row.len() as u16 - 1);
+    let scaled_row_height =
+        ((options.row_width - spacing_pixels) / total_aspect_ratio).min(max_row_height);
+
+    let mut actual_row_width = spacing_pixels;
+    let mut left = 0.0;
+    // SAFETY: this slice's length is guaranteed to be a multiple of 4
+    let row_positions = unsafe { row.as_chunks_unchecked_mut::<4>() };
+    for i in 0..aspect_ratio_row.len() {
+        let pos = &mut row_positions[i];
+        let width = aspect_ratio_row[i] * scaled_row_height;
+        pos[0] = top;
+        pos[1] = left;
+        pos[2] = width;
+        pos[3] = scaled_row_height;
+        left += width + options.spacing;
+        actual_row_width += width;
+    }
+    // SAFETY: these indices are guaranteed to be within the vector's bounds
+    unsafe {
+        *positions.get_unchecked_mut(0) = actual_row_width.max(max_actual_row_width).ceil();
+        *positions.get_unchecked_mut(1) = (top + scaled_row_height).ceil();
+    }
+    positions.into_iter().map(|val| val as i32).collect()
+}
diff --git a/tests/lib.rs b/tests/lib.rs
new file mode 100644
index 0000000..14dc2c0
--- /dev/null
+++ b/tests/lib.rs
@@ -0,0 +1,427 @@
+use justified_layout::get_justified_layout;
+use wasm_bindgen_test::*;
+
+wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
+
+#[wasm_bindgen_test]
+fn fits_perfectly_on_one_row() {
+    let input: Vec<f32> = vec![1.0, 1.0, 1.0];
+    let row_width = 900.0;
+    let row_height = 300.0;
+    let spacing = 0.0;
+    let height_tolerance = 0.0;
+
+    let layout = get_justified_layout(
+        input.as_slice(),
+        row_height,
+        row_width,
+        spacing,
+        height_tolerance,
+    );
+    assert_eq!(layout.len(), 16);
+    let max_row_width = layout[0];
+    assert_eq!(max_row_width, 900);
+
+    let max_row_height = layout[1];
+    assert_eq!(max_row_height, 300);
+
+    let [top1, left1, width1, height1] = layout[4..8] else {
+        unreachable!()
+    };
+    assert_eq!(top1, 0);
+    assert_eq!(left1, 0);
+    assert_eq!(width1, 300);
+    assert_eq!(height1, 300);
+
+    let [top2, left2, width2, height2] = layout[8..12] else {
+        unreachable!()
+    };
+    assert_eq!(top2, 0);
+    assert_eq!(left2, width1);
+    assert_eq!(width2, 300);
+    assert_eq!(height2, 300);
+
+    let [top3, left3, width3, height3] = layout[12..16] else {
+        unreachable!()
+    };
+    assert_eq!(top3, 0);
+    assert_eq!(left3, width1 + width2);
+    assert_eq!(width3, 300);
+    assert_eq!(height3, 300);
+}
+
+#[wasm_bindgen_test]
+fn applies_spacing() {
+    let input: Vec<f32> = vec![1.0, 1.0, 1.0];
+    let row_width = 904.0;
+    let row_height = 300.0;
+    let spacing = 2.0;
+    let height_tolerance = 0.0;
+
+    let layout = get_justified_layout(
+        input.as_slice(),
+        row_height,
+        row_width,
+        spacing,
+        height_tolerance,
+    );
+    assert_eq!(layout.len(), 16);
+    let max_row_width = layout[0];
+    assert_eq!(max_row_width, 904);
+
+    let max_row_height = layout[1];
+    assert_eq!(max_row_height, 300);
+
+    let [top1, left1, width1, height1] = layout[4..8] else {
+        unreachable!()
+    };
+    assert_eq!(top1, 0);
+    assert_eq!(left1, 0);
+    assert_eq!(width1, 300);
+    assert_eq!(height1, 300);
+
+    let [top2, left2, width2, height2] = layout[8..12] else {
+        unreachable!()
+    };
+    assert_eq!(top2, 0);
+    assert_eq!(left2, width1 + spacing as i32);
+    assert_eq!(width2, 300);
+    assert_eq!(height2, 300);
+
+    let [top3, left3, width3, height3] = layout[12..16] else {
+        unreachable!()
+    };
+    assert_eq!(top3, 0);
+    assert_eq!(left3, width1 + spacing as i32 + width2 + spacing as i32);
+    assert_eq!(width3, 300);
+    assert_eq!(height3, 300);
+}
+
+#[wasm_bindgen_test]
+fn expands_row_based_on_height_tolerance() {
+    let input: Vec<f32> = vec![1.0, 1.0, 1.0];
+    let row_width = 1000.0;
+    let row_height = 300.0;
+    let spacing = 2.0;
+    let height_tolerance = 0.1;
+
+    let layout = get_justified_layout(
+        input.as_slice(),
+        row_height,
+        row_width,
+        spacing,
+        height_tolerance,
+    );
+    assert_eq!(layout.len(), 16);
+    let max_row_width = layout[0];
+    assert_eq!(max_row_width, 994);
+
+    let max_row_height = layout[1];
+    assert_eq!(max_row_height, 330);
+
+    let [top1, left1, width1, height1] = layout[4..8] else {
+        unreachable!()
+    };
+    assert_eq!(top1, 0);
+    assert_eq!(left1, 0);
+    assert_eq!(width1, 330);
+    assert_eq!(height1, 330);
+
+    let [top2, left2, width2, height2] = layout[8..12] else {
+        unreachable!()
+    };
+    assert_eq!(top2, 0);
+    assert_eq!(left2, width1 + spacing as i32);
+    assert_eq!(width2, 330);
+    assert_eq!(height2, 330);
+
+    let [top3, left3, width3, height3] = layout[12..16] else {
+        unreachable!()
+    };
+    assert_eq!(top3, 0);
+    assert_eq!(left3, width1 + spacing as i32 + width2 + spacing as i32);
+    assert_eq!(width3, 330);
+    assert_eq!(height3, 330);
+}
+
+#[wasm_bindgen_test]
+fn adds_second_row_due_to_spacing() {
+    let input: Vec<f32> = vec![1.0, 1.0, 1.0];
+    let row_width = 900.0;
+    let row_height = 300.0;
+    let spacing = 2.0;
+    let height_tolerance = 0.0;
+
+    let layout = get_justified_layout(
+        input.as_slice(),
+        row_height,
+        row_width,
+        spacing,
+        height_tolerance,
+    );
+    assert_eq!(layout.len(), 16);
+    let max_row_width = layout[0];
+    assert_eq!(max_row_width, 602);
+
+    let max_row_height = layout[1];
+    assert_eq!(max_row_height, 602);
+
+    let [top1, left1, width1, height1] = layout[4..8] else {
+        unreachable!()
+    };
+    assert_eq!(top1, 0);
+    assert_eq!(left1, 0);
+    assert_eq!(width1, 300);
+    assert_eq!(height1, 300);
+    //
+    let [top2, left2, width2, height2] = layout[8..12] else {
+        unreachable!()
+    };
+    assert_eq!(top2, 0);
+    assert_eq!(left2, width1 + spacing as i32);
+    assert_eq!(width2, 300);
+    assert_eq!(height2, 300);
+
+    let [top3, left3, width3, height3] = layout[12..16] else {
+        unreachable!()
+    };
+    assert_eq!(top3, (row_height + spacing) as i32);
+    assert_eq!(left3, 0);
+    assert_eq!(width3, 300);
+    assert_eq!(height3, 300);
+}
+
+#[wasm_bindgen_test]
+fn positions_boxes_with_different_aspect_ratios() {
+    let input: Vec<f32> = vec![16.0 / 9.0, 2.0, 9.0 / 16.0];
+    let row_width = 900.0;
+    let row_height = 300.0;
+    let spacing = 2.0;
+    let height_tolerance = 0.0;
+
+    let layout = get_justified_layout(
+        input.as_slice(),
+        row_height,
+        row_width,
+        spacing,
+        height_tolerance,
+    );
+    assert_eq!(layout.len(), 16);
+    let max_row_width = layout[0];
+    assert_eq!(max_row_width, 771);
+
+    let max_row_height = layout[1];
+    assert_eq!(max_row_height, 602);
+
+    let [top1, left1, width1, height1] = layout[4..8] else {
+        unreachable!()
+    };
+    assert_eq!(top1, 0);
+    assert_eq!(left1, 0);
+    assert_eq!(width1, (300.0 * (16.0 / 9.0)) as i32);
+    assert_eq!(height1, 300);
+    //
+    let [top2, left2, width2, height2] = layout[8..12] else {
+        unreachable!()
+    };
+    assert_eq!(top2, height1 + spacing as i32);
+    assert_eq!(left2, 0);
+    assert_eq!(width2, 300 * 2);
+    assert_eq!(height2, 300);
+
+    let [top3, left3, width3, height3] = layout[12..16] else {
+        unreachable!()
+    };
+    assert_eq!(top3, height1 + spacing as i32);
+    assert_eq!(left3, width2 + spacing as i32);
+    assert_eq!(width3, (300.0 * (9.0 / 16.0)) as i32);
+    assert_eq!(height3, 300);
+}
+
+#[wasm_bindgen_test]
+fn scales_boxes_with_different_aspect_ratios_when_using_height_tolerance() {
+    let input: Vec<f32> = vec![16.0 / 9.0, 2.0, 9.0 / 16.0];
+    let row_width = 900.0;
+    let row_height = 300.0;
+    let spacing = 2.0;
+    let height_tolerance = 0.2;
+
+    let layout = get_justified_layout(
+        input.as_slice(),
+        row_height,
+        row_width,
+        spacing,
+        height_tolerance,
+    );
+    assert_eq!(layout.len(), 16);
+    let max_row_width = layout[0];
+    assert_eq!(max_row_width, 900);
+
+    let max_row_height = layout[1];
+    assert_eq!(max_row_height, 712 + 1); // 1 to account for ceil()
+
+    let [top1, left1, width1, height1] = layout[4..8] else {
+        unreachable!()
+    };
+    assert_eq!(top1, 0);
+    assert_eq!(left1, 0);
+    assert_eq!(width1, 640);
+    assert_eq!(height1, 360);
+    //
+    let [top2, left2, width2, height2] = layout[8..12] else {
+        unreachable!()
+    };
+    assert_eq!(top2, height1 + spacing as i32);
+    assert_eq!(left2, 0);
+    assert_eq!(width2, 700);
+    assert_eq!(height2, 350);
+
+    let [top3, left3, width3, height3] = layout[12..16] else {
+        unreachable!()
+    };
+    assert_eq!(top3, height1 + spacing as i32);
+    assert_eq!(left3, width2 + spacing as i32);
+    assert_eq!(width3, 197);
+    assert_eq!(height3, 350);
+}
+
+#[wasm_bindgen_test]
+fn one_square_box_on_each_row() {
+    let input: Vec<f32> = vec![1.0, 1.0, 1.0];
+    let row_width = 599.0;
+    let row_height = 300.0;
+    let spacing = 2.0;
+    let height_tolerance = 0.0;
+
+    let layout = get_justified_layout(
+        input.as_slice(),
+        row_height,
+        row_width,
+        spacing,
+        height_tolerance,
+    );
+    assert_eq!(layout.len(), 16);
+    let max_row_width = layout[0];
+    assert_eq!(max_row_width, 300);
+
+    let max_row_height = layout[1];
+    assert_eq!(max_row_height, 904);
+
+    let [top1, left1, width1, height1] = layout[4..8] else {
+        unreachable!()
+    };
+    assert_eq!(top1, 0);
+    assert_eq!(left1, 0);
+    assert_eq!(width1, 300);
+    assert_eq!(height1, 300);
+
+    let [top2, left2, width2, height2] = layout[8..12] else {
+        unreachable!()
+    };
+    assert_eq!(top2, height1 + spacing as i32);
+    assert_eq!(left2, 0);
+    assert_eq!(width2, 300);
+    assert_eq!(height2, 300);
+
+    let [top3, left3, width3, height3] = layout[12..16] else {
+        unreachable!()
+    };
+    assert_eq!(top3, height1 + spacing as i32 + height2 + spacing as i32);
+    assert_eq!(left3, 0);
+    assert_eq!(width3, 300);
+    assert_eq!(height3, 300);
+}
+
+#[wasm_bindgen_test]
+fn different_shaped_boxes_on_each_row() {
+    let input: Vec<f32> = vec![16.0 / 9.0, 2.0, 9.0 / 16.0];
+    let row_width = 600.0;
+    let row_height = 300.0;
+    let spacing = 2.0;
+    let height_tolerance = 0.0;
+
+    let layout = get_justified_layout(
+        input.as_slice(),
+        row_height,
+        row_width,
+        spacing,
+        height_tolerance,
+    );
+    assert_eq!(layout.len(), 16);
+    let max_row_width = layout[0];
+    assert_eq!(max_row_width, 600);
+
+    let max_row_height = layout[1];
+    assert_eq!(max_row_height, 904);
+
+    let [top1, left1, width1, height1] = layout[4..8] else {
+        unreachable!()
+    };
+    assert_eq!(top1, 0);
+    assert_eq!(left1, 0);
+    assert_eq!(width1, 533);
+    assert_eq!(height1, 300);
+    //
+    let [top2, left2, width2, height2] = layout[8..12] else {
+        unreachable!()
+    };
+    assert_eq!(top2, height1 + spacing as i32);
+    assert_eq!(left2, 0);
+    assert_eq!(width2, 600);
+    assert_eq!(height2, 300);
+
+    let [top3, left3, width3, height3] = layout[12..16] else {
+        unreachable!()
+    };
+    assert_eq!(top3, height1 + spacing as i32 + height2 + spacing as i32);
+    assert_eq!(left3, 0);
+    assert_eq!(width3, 168);
+    assert_eq!(height3, 300);
+}
+
+#[wasm_bindgen_test]
+fn one_box_on_each_row_with_scaling() {
+    let input: Vec<f32> = vec![16.0 / 9.0, 2.0, 9.0 / 16.0];
+    let row_width = 600.0;
+    let row_height = 300.0;
+    let spacing = 2.0;
+    let height_tolerance = 0.15;
+
+    let layout = get_justified_layout(
+        input.as_slice(),
+        row_height,
+        row_width,
+        spacing,
+        height_tolerance,
+    );
+    assert_eq!(layout.len(), 16);
+    let max_row_width = layout[0];
+    assert_eq!(max_row_width, 600);
+
+    let max_row_height = layout[1];
+    assert_eq!(max_row_height, 337 + 2 + 300 + 2 + 345 + 1); // 1 to account for ceil()
+
+    let [top1, left1, width1, height1] = layout[4..8] else {
+        unreachable!()
+    };
+    assert_eq!(top1, 0);
+    assert_eq!(left1, 0);
+    assert_eq!(width1, 600);
+    assert_eq!(height1, 337);
+    //
+    let [top2, left2, width2, height2] = layout[8..12] else {
+        unreachable!()
+    };
+    assert_eq!(top2, height1 + spacing as i32);
+    assert_eq!(left2, 0);
+    assert_eq!(width2, 600);
+    assert_eq!(height2, 300);
+
+    let [top3, left3, width3, height3] = layout[12..16] else {
+        unreachable!()
+    };
+    assert_eq!(top3, height1 + spacing as i32 + height2 + spacing as i32);
+    assert_eq!(left3, 0);
+    assert_eq!(width3, 194);
+    assert_eq!(height3, 345);
+}