Image Format Converter
Convert JPG ↔ PNG ↔ WebP in your browser. Batch, quality control, lossless WebP.
published
- [FREE]
- [NO_SIGNUP]
- [NO_UPLOAD]
An image format converter turns JPG, PNG, and WebP files into each other — without uploading them. This tool runs jsquash WebAssembly codecs inside your browser tab, so your photos and graphics never touch a server. Quality slider for lossy output, lossless WebP toggle, batch with zip download.
Need to resize images to specific pixel dimensions instead of (or in addition to) changing format? Pair this with the Image Size Converter — same codecs, same privacy posture, lets you set width × height. Both tools batch and zip.
How to use the image format converter
- Drop or pick images. JPG, PNG, and WebP are supported as both input and output. HEIC and AVIF are not in this version (see FAQ for why).
- Pick the output format. JPG for universal compatibility, PNG for lossless + transparency, WebP for the smallest modern format that still handles both.
- Tune quality. Lossy formats (JPG, WebP) get a 1–100 slider. PNG is lossless, no knob. Toggle Lossless WebP for pixel-perfect transparent images.
- Convert all. Two files process in parallel. Per-file Download button appears as each finishes. Download all packages every completed result into a single zip.
Common conversions and when to do them
| From → To | When to do it |
|---|---|
| WebP → JPG | Downstream tool rejects WebP (older CMS, certain Windows/Mac apps, some photo printers). Quality 85–90 is visually identical. |
| WebP → PNG | You need lossless + transparency in a tool that lacks WebP support. |
| PNG → JPG | Smaller files for photos that don’t need transparency. Quality 80–85 for the web. Note: transparency flattens to black. |
| PNG → WebP | Smallest modern format. Lossless WebP if the PNG has transparency or sharp edges. Lossy WebP for photographic PNGs. |
| JPG → WebP | 25–35% smaller for the same quality. Default modern choice for website hero images. |
| JPG → PNG | Rarely useful (PNG is bigger and JPG is already lossy). Sometimes needed for pipelines that require PNG input. |
Lossless vs lossy in two sentences
Lossy (JPG, default WebP) discards pixel data the human eye won’t notice in exchange for much smaller files. Once thrown away, the data is gone — re-encoding a JPG to JPG at higher quality won’t recover the detail.
Lossless (PNG, lossless WebP) keeps every pixel exactly. Re-encoding lossless → lossless is byte-for-byte recoverable. Use for screenshots, logos, line art, and anything where compression artifacts would be visible.
Transparency note
JPG has no alpha channel. Converting a PNG with transparency to JPG will flatten the transparent areas against a solid background (the jsquash encoder uses black). If the destination tool needs transparency:
- Convert to WebP instead (supports alpha).
- Or keep the original PNG.
- Or flatten against your specific background color first using an image editor.
Metadata gets stripped
Re-encoding through jsquash strips:
- EXIF (camera model, GPS, capture time, lens metadata)
- ICC color profiles (color management may shift slightly between input and output)
- XMP (Adobe metadata, copyright fields)
- Thumbnails embedded in JPG
This is a side-effect, not a feature — but if your goal is specifically removing metadata, use the EXIF Viewer & Stripper which removes EXIF without re-encoding pixels (so you keep the original quality bit-for-bit).
How it compares
| bytefork.tools | cloudconvert.com | convertio.co | |
|---|---|---|---|
| Runs in browser | ✓ (WASM) | ✗ (uploads to server) | ✗ (uploads to server) |
| Batch + zip download | ✓ | ✓ paid tier | partial |
| Quality slider | ✓ 1–100 | ✓ | ✓ |
| Lossless WebP | ✓ | ✓ | partial |
| Sign-in / file-size cap | ✗ | required for >25 MB | required for >100 MB |
| Ad-free | ✓ | ✓ | ✗ |
| Files leave your device | ✗ never | ✓ | ✓ |
Privacy and security
A static HTML page with a small JavaScript bundle. The codec WASM modules (jsquash JPEG, PNG, WebP) load on first use and run entirely in your browser tab. Files are read by FileReader / Blob APIs and stay in memory. The Network tab in DevTools confirms it — once codecs load, no further requests fire when you convert or download.
Related tools
- Image Compressor — same codecs, focus on size reduction without format change.
- Image Size Converter — resize while preserving format. Pair with this tool to resize and convert in one flow.
- EXIF Viewer & Stripper — strip metadata without re-encoding pixels.
- Favicon Generator — different output target: ICO + multiple PNG sizes from one source.
Frequently asked questions
Is my image uploaded anywhere?
No. Decoding and re-encoding both run via WebAssembly (jsquash) in your browser tab. Files are read by FileReader / Blob.arrayBuffer and stay in memory. Open DevTools → Network: no requests fire after the codec WASM downloads, and the codec downloads are anonymous static fetches without your image data.
Which formats are supported?
Source: JPG, PNG, WebP. Output: JPG, PNG, WebP. HEIC and AVIF are intentionally not supported in this version — HEIC requires a 700 KB libheif-js polyfill that bloats the bundle, and AVIF encode is heavy. If you need HEIC→JPG specifically, macOS Preview, Windows Photos, or the iCloud web app convert without an extra tool.
When should I convert to WebP?
WebP averages 25-35% smaller than JPG for the same visual quality, and supports both lossy (like JPG) and lossless (like PNG) modes. Every major browser supports it as of 2020. For website images, WebP is the default modern choice. Keep JPG copies if older email clients or third-party tools (Slack inline preview, some CMS imports) reject WebP.
When should I convert WebP to JPG?
When a downstream tool refuses WebP. Common cases: an older CMS, a printer driver, Adobe products on Windows 7-8, certain photo printers. Convert at quality 85-90 for visually-identical output.
What does the quality slider do?
For JPG and lossy WebP, it controls the encoder's quality factor (1–100). 85 is the conventional default — visually identical to the original for most photos, with a major size cut. Drop to 70 for thumbnails, push to 95+ for archival. PNG has no quality knob because it's lossless.
What is lossless WebP?
A second WebP mode that compresses without throwing away pixel data, like PNG. Larger than lossy WebP but still usually smaller than the equivalent PNG. Use it for logos, screenshots, line art — anything where you would have picked PNG over JPG.
Does it preserve transparency?
Yes for PNG and WebP. JPG has no alpha channel, so converting a transparent PNG to JPG flattens the transparency against black (the encoder default). Convert to WebP instead if you need transparency.
Does it preserve EXIF and other metadata?
No — re-encoding through jsquash strips all metadata (EXIF, ICC profiles, XMP). Use the [EXIF Viewer & Stripper](/exif-viewer/) if you specifically want to remove metadata from an existing image without re-encoding the pixels.
Can I batch convert hundreds of files?
Yes. Drop many files, hit Convert all, and the tool processes two at a time concurrently. Download-all packages every successful result into a zip. The browser is the only memory ceiling — modern desktops handle 50-100 typical photos without trouble.
Is the image converter really free?
Yes. No signup, no account, no ads, no telemetry on your input. The source is on the project repository.