ConvertIt

Drop a file, pick an output format, download it. Images, video, audio, documents and 3D models. Everything is decoded and re-encoded in the browser tab, so nothing gets uploaded.

What converts to what

Images (Canvas / OffscreenCanvas)

• PNG to JPEG, WebP, AVIF
• JPEG to PNG, WebP, AVIF
• WebP to PNG, JPEG, AVIF
• AVIF to PNG, JPEG, WebP
• HEIC to JPEG, PNG, WebP, decoded through heic2any
• GIF to PNG, JPEG, WebP as a first frame, or to MP4 and WebM if animated
• BMP to PNG, JPEG, WebP
• SVG to PNG, JPEG, rasterised at 2x
• Any image to PDF

Video (ffmpeg.wasm)

• MP4 to WebM, GIF
• WebM to MP4, GIF
• MOV to MP4, WebM
• MKV to MP4, WebM
• Any video to MP3 or WAV audio

Audio (Web Audio + lamejs)

• MP3 to WAV, OGG
• WAV to MP3, OGG
• FLAC to MP3, WAV, OGG
• OGG to MP3, WAV
• M4A to MP3, WAV

Documents (pdf-lib + pdfjs-dist)

• PDF to PNG or JPEG, all pages stacked
• Several images into one PDF
• TXT and Markdown to PDF, paginated with wrapped text

3D models (three.js)

• OBJ to GLB, STL, PLY
• STL to GLB, OBJ, PLY
• PLY to GLB, OBJ, STL
• glTF / GLB to OBJ, STL, PLY
• Collada (DAE) to GLB, OBJ, STL, PLY
• FBX to GLB, OBJ, STL, PLY
• 3MF to GLB, OBJ, STL, PLY

3D conversion covers mesh geometry. Materials survive into GLB and are dropped for the geometry-only formats. Animations, skeletons and Draco-compressed glTF are out of scope, and CAD formats like STEP and IGES aren't feasible in the browser.

Running it

bun install
bun run dev      # http://localhost:3000
bun run lint

The pdfjs worker is vendored at public/pdf.worker.min.mjs. The ffmpeg WASM core is fetched from a CDN at runtime and turned into a blob URL so it still runs entirely client-side.

Built with

Next.js 16, TypeScript, Tailwind CSS 4 and shadcn/ui, with ffmpeg.wasm (lazy-loaded, single-threaded core so COEP headers aren't needed) for video and audio, Canvas and OffscreenCanvas for images, Web Audio plus @breezystack/lamejs for audio encoding, pdf-lib and pdfjs-dist for PDF, three.js for 3D, and heic2any for HEIC. Package manager is bun.

Privacy

Conversion is local. Files are not uploaded, there is no analytics or tracking, and localStorage holds nothing but a theme preference.

Deploying

Import the repo on Vercel. Next.js is auto-detected, the defaults are right, and there are no environment variables. It works on any static host too.

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Jeffrey Hamilton · GitHub · buy me a coffee