About ConvertMyPic
ConvertMyPic is a free image converter that runs entirely inside your browser. Drop in a PNG, JPG, WebP, AVIF, or HEIC file and convert it to any of the others — the decode and encode happen on your own device, using the same production codecs that ship inside Chrome and Firefox, compiled to WebAssembly. Nothing is uploaded, nothing is stored, and there is no account to create. This page explains what the tool is, where it came from, and exactly how it works under the hood.
Open the converter →What ConvertMyPic is
ConvertMyPic is a browser-based image converter for the five formats most people actually need to move between: PNG, JPG, WebP, AVIF, and HEIC. You drop a file onto the page, choose an output format and quality, preview the result, and download it. There is no upload step, no queue, no email gate, and no watermark. The tool is free to use because there is no server doing the work — the conversion runs on the device in front of you, in the browser tab you already have open. That design choice is the whole product. Most online converters send your file to a server, process it there, and send a download link back. ConvertMyPic does the opposite: it ships the codecs to your browser once, then runs every conversion locally. The practical result is that your photos and screenshots never leave your machine, conversions start the instant you drop a file rather than after an upload completes, and — after the first visit — the app keeps working with no network connection at all, because it is a Progressive Web App that caches its own code. The scope is deliberately narrow. ConvertMyPic converts between raster image formats and lets you tune compression quality. It is not a photo editor, a RAW developer, or a batch-processing pipeline. Keeping the surface small is what lets the tool stay fast, stay private, and stay honest about what it does.
Where ConvertMyPic comes from
ConvertMyPic was built around one conviction: image conversion should never require handing your file to a stranger's server. The approach the tool depends on is to compile the real image codecs to WebAssembly, run them directly in the browser, and give people a side-by-side preview so they can see the quality-versus-size tradeoff before they commit. That architecture is what makes a genuinely private, genuinely fast converter possible, so it is the foundation everything else is built on. What ConvertMyPic offers falls into four areas. First, HEIC support: Apple's HEIC format is awkward to open on Android, in web forms, and in older desktop software, so we integrated the libheif decoder as a WebAssembly module, which means iPhone photos work directly in the tool without any pre-conversion step. Second, format-specific landing pages: instead of a single generic app, ConvertMyPic provides dedicated, documented pages for the conversions people search for — HEIC to JPG, JPG to AVIF, WebP to PNG with transparency, and so on — each one explaining the format tradeoffs honestly rather than just offering a button. Third, a consumer-friendly brand and interface aimed at people who are not codec engineers and simply want a file that opens everywhere. Fourth, a hardened offline PWA so the whole thing keeps working without a connection. The heavy lifting is done by mature, battle-tested codecs — mozJPEG, oxiPNG, libwebp, libaom and libavif, and libheif — each maintained by its own open-source community. ConvertMyPic brings those engines together in the browser, wraps them in a private-by-default interface, and documents what they actually do. Crediting the codec maintainers plainly is more useful than implying we wrote the encoders ourselves.
How it works under the hood
When you drop a file onto the page, the browser first decodes it into a raw bitmap. For PNG, JPG, and WebP the browser's own image pipeline and an HTML canvas handle decoding; for AVIF and HEIC, dedicated WebAssembly decoders take over because not every browser can decode those natively. Once the image is a raw RGBA pixel buffer, it is handed to the encoder for your chosen output format. Every encode and decode step runs inside a Web Worker, which keeps the interface responsive and — more importantly — means the pixel data never touches the network. The codecs are the real ones, not approximations. JPG output uses mozJPEG, Mozilla's optimised JPEG encoder, which applies trellis quantisation to produce files that are typically around 10 to 15 percent smaller than a classic libjpeg file at the same visual quality (a representative figure — actual savings depend on the image). PNG output uses oxiPNG, a Rust-based lossless PNG optimiser that runs multi-pass DEFLATE compression without altering a single pixel value. WebP output uses libwebp, Google's reference WebP implementation and the same library that ships inside Chrome. AVIF output uses libaom and libavif — the Alliance for Open Media's AV1 encoder and AVIF container library — which deliver the strongest compression of the bunch at the cost of slower encode times. HEIC decoding uses libheif, the open-source HEIF/HEIC library, so Apple's High Efficiency photos can be read directly. All of these are mature, widely deployed C and Rust libraries compiled to WebAssembly. WebAssembly runs them at close to native speed inside the browser sandbox, which is what makes a fully local converter practical rather than a novelty. You can verify the privacy claim yourself: open your browser's developer tools, switch to the Network tab, and watch a conversion. You will see the initial page and codec download, and then zero outbound data requests while the file is converted.
Why on-device conversion matters
Running everything locally is not a marketing angle; it changes what the tool can promise. The first thing it changes is privacy. A photo can carry far more than an image — GPS coordinates of where it was taken, the device that captured it, a timestamp, and of course whatever is in the frame. When conversion happens on a server, you are trusting an operator you cannot see to not retain, log, train on, or leak that file. With on-device conversion there is no such operator and no such trust required, because the file simply never leaves your machine. That matters for personal photos, and it matters even more for screenshots of private messages, identity documents, medical paperwork, or anything covered by a confidentiality obligation. The second thing it changes is speed. A server-based converter has to upload your file, wait in a processing queue, and download the result. For a large photo on a typical home connection, the upload alone can dwarf the actual conversion time. ConvertMyPic skips the round trip entirely — the file is already on your device, so conversion begins the moment you drop it. The third is offline capability. Because ConvertMyPic is a Progressive Web App, a service worker caches the app shell and every WebAssembly codec after your first visit. From then on you can convert images on a plane, on a train, or with the network switched off completely. The fourth is cost: there are no servers to run, so there is nothing to charge for and no incentive to gate the tool behind an account or a paywall. The tool is free as a direct consequence of how it is built.
On-device versus server-based converters
A representative comparison of the two architectures. ConvertMyPic uses the on-device model in every column.
| Concern | On-device (ConvertMyPic) | Server-based converter |
|---|---|---|
| Where your file goes | Stays on your device | Uploaded to a remote server |
| Privacy of contents | Operator never sees the file | Trust required; retention varies |
| Time to start | Instant — no upload step | Waits for upload, then a queue |
| Works offline | Yes, after first load (PWA) | No — requires a connection |
| Cost model | Free; no servers to run | Often gated, ad-funded, or capped |
Who it's for
ConvertMyPic is built for three kinds of people. The first is the iPhone owner with a folder full of HEIC photos that will not open on a friend's Android phone, will not upload to a web form, or show up as a broken attachment in Outlook. For them the tool turns a HEIC into a JPG or PNG that opens everywhere, without installing software or signing up for anything. The second is the developer or designer shrinking assets for the web. WebP and AVIF can cut image payloads dramatically, and the side-by-side preview makes it easy to find the quality setting where the file is small but still looks right. Because the real libwebp and libaom encoders are doing the work, the output is the same you would get from a command-line build step — just without the build step. The third, and largest, is simply anyone who does not want to hand a private photo to a random server to convert it. If a file is sensitive — a passport scan, a screenshot of a bank statement, a medical image, or just a personal photo you would rather not see logged somewhere — an on-device converter is the only kind that can genuinely promise the file stays with you. ConvertMyPic exists so that promise is the default, not a premium feature.
FAQ
Is ConvertMyPic really free, and how?
Yes, completely free, with no account, paywall, or usage cap. It is free because there are no servers doing the conversion — the codecs run in your own browser, so there is no per-conversion cost to recover. The only thing our hosting serves is the app code and the WebAssembly codec files, which download once and then cache on your device.
Do my images get uploaded anywhere?
No. Every conversion runs locally in your browser using WebAssembly codecs inside a Web Worker. The image data never leaves your device. You can verify this yourself: open your browser developer tools, switch to the Network tab, and run a conversion — you will see the initial page and codec download and then zero outbound data requests while the file is processed.
How is ConvertMyPic different from a server-based online converter?
A server-based converter uploads your file to a remote machine, processes it there, and sends a download link back, which means an operator you cannot see has to handle your file. ConvertMyPic does the opposite: it ships the codecs to your browser once and runs every conversion locally, so the image never leaves your device. On top of that on-device engine it adds HEIC decoding via libheif, format-specific converter pages, a consumer-friendly interface, and a hardened offline PWA. The conversion work itself is done by mature open-source codecs — mozJPEG, oxiPNG, libwebp, libaom and libavif, and libheif — each maintained by its own community.
Which formats and codecs does it use?
ConvertMyPic converts between PNG, JPG, WebP, AVIF, and HEIC. JPG encoding uses mozJPEG, PNG uses oxiPNG, WebP uses libwebp, AVIF uses libaom and libavif, and HEIC is decoded with libheif. All of these are mature open-source codecs compiled to WebAssembly so they run on-device at close to native speed.
Related conversions
- HEIC to JPG — Turn iPhone HEIC photos into universally compatible JPGs.
- JPG to AVIF — Shrink JPGs with the AV1-based AVIF encoder for the web.
- AVIF converter — Convert to and from AVIF, with format tradeoffs explained.