Image Converter — JPG, PNG, WebP & AVIF Without Uploading

Batch-convert images between PNG, JPEG, WebP, and AVIF with a custom naming template.

Converting a folder of mixed PNGs, JPEGs, and WebP files into one shared output format is a batch job that needs one target codec applied consistently, not per-image quality tuning. This tool decodes every queued file through the browser's native createImageBitmap and re-encodes all of them to whichever of MozJPEG, OxiPNG, WebP, or AVIF you pick, with a naming scheme that previews the exact output filenames before you run anything.

How to convert images

Drop your images or click the upload zone to choose them; PNG, JPEG, WebP, AVIF and GIF files can be mixed in one queue.
Under Convert all images to, pick the target format and set its quality, lossless toggle or OxiPNG level.
Check the output filename shown on each queue row, and switch to a custom template with {name}, {n} and {ext} tokens if you want a different scheme.
Press Convert all, then Download: one finished file saves directly, and two or more arrive together in a ZIP.

One target format for the whole batch

This is the deliberate design difference from a per-image compressor: every file in the queue converts to the same target codec and the same quality/lossless/level settings, since the point of a converter is standardizing a format across a batch rather than hand-tuning each file. It reuses the exact codec metadata and option logic from this site's image compressor — MozJPEG's quality-only model, OxiPNG's always-lossless optimization levels, and WebP/AVIF's lossless toggle plus 1-100 quality scale all behave identically here.

The queue accepts as many files as you add, but on the free tier a single Convert all run covers up to 40 images. For a larger folder, convert 40, download them, press Clear all and queue the next group; Pro removes the per-run ceiling.

Image converter input and output formats

Input: anything your browser can decode through its own image engine, which covers PNG, JPEG, WebP, AVIF, GIF and BMP in current browsers. HEIC only loads where the browser itself supports it; no HEIC decoder is bundled.
Output: JPEG (MozJPEG), PNG (OxiPNG), WebP or AVIF, with one target format applied to every file in the run.
Free tier: up to 40 images per Convert all run, with no limit on how many runs you make and no watermark. Pro converts any number in one run.
Downloads: a single converted file saves directly, while two or more are bundled into one ZIP archive.

Popular image conversions

WebP to PNG: keeps any transparency and gives a file that every editor and older app can open.
WebP to JPG: the smallest widely compatible option for photos saved from websites; transparent areas are lost.
PNG to JPG: shrinks photos and screenshots with no transparency, but a transparent background cannot survive the switch.
JPG to PNG: useful when a tool demands PNG, though it cannot restore detail the JPEG already threw away.
PNG to WebP and JPG to WebP: usually a much lighter file for a website with little visible change.
AVIF to JPG: turns a modern AVIF image into something older software and email clients accept.

Decode is native, encode is WebAssembly

Decoding a source file — whatever format it arrives in — goes through the browser's own createImageBitmap and an OffscreenCanvas 2D context, which is why this converter accepts essentially anything the browser can display, not just the four formats it can output. Re-encoding then runs through the same jSquash WebAssembly codec builds the compressor uses: real MozJPEG, real OxiPNG, real libwebp, real libavif, not a JavaScript approximation. Alpha transparency is detected per-file by sampling decoded pixels on a stride, feeding the same recommended-settings heuristic the compressor uses.

Filenames you can trust before you download

Two naming modes are available: a default scheme that simply swaps each source file's extension for the target format's, or a custom token template you control. Either way, the exact resolved output filenames are computed live off the same resolver function the actual export uses — the preview list you see before converting and the files you actually get after converting can never drift apart, because there's exactly one naming implementation shared between them, not a display copy and an export copy that could disagree.

The resolver also handles collisions: if a custom template or an extension swap would produce two identical output names, later files get deduplicated rather than silently overwriting each other in the export.

Batch throughput comes from a real worker pool

Decoding and re-encoding both run in a pool of Web Workers sized to your device's reported CPU core count, capped at eight, so a large batch processes several files concurrently instead of one at a time freezing the tab. Every byte handled — decode input, re-encoded output — stays inside your browser; nothing in this pipeline issues a network request.

Which image format should you choose?

JPEG for photographs that need to open everywhere, from old phones to email attachments.
PNG for screenshots, logos and anything with transparency or sharp text, where lossless output matters more than size.
WebP as the everyday web default: smaller than JPEG and PNG, with transparency, and supported by all current browsers.
AVIF when the smallest file matters most and the destination is known to accept it; it encodes more slowly than the others.

Where a straight format swap isn't enough

Converting a JPEG to a lossless format like PNG does not recover detail the original JPEG compression already discarded — you get a lossless copy of already-lossy data, not the original photo back.
Converting from a format with transparency (PNG, WebP with alpha) to plain JPEG will flatten or lose the alpha channel, since JPEG has no transparency support at all — check the alpha detection result before batch-converting graphics with transparent backgrounds.
This tool applies one target format and one setting to every file in the batch; if different images genuinely need different quality levels (a batch mixing photos and flat icons, say), running them through the per-image compressor instead will usually give better results than one shared setting.
AVIF encode is noticeably slower per image than the other three codecs — a large batch targeting AVIF will take longer to finish than the same batch targeting MozJPEG or WebP, even though the worker pool parallelizes across files.

Questions people ask about Image Converter

Can I convert a batch of different source formats to one target format at once?: Yes — that's the tool's core purpose. Queue PNGs, JPEGs, WebPs, or any browser-decodable image together, pick one target codec, and every file converts to that same format and quality setting in one batch run, with live filename previews before you commit.
What's the difference between this and the Image Compressor?: The compressor lets you tune quality per image and shows a live SSIM comparison for each one — suited to squeezing size out of a handful of photos. This converter applies one shared target format and setting across an entire batch, prioritizing consistent output format over per-image quality tuning.
Does converting to WebP or AVIF always produce a smaller file than JPEG?: Usually, at equivalent visual quality, but not guaranteed for every image — a very small or already-optimized source file can occasionally come out larger in a newer container due to format overhead. Check the reported output size for your specific files rather than assuming.
How does the custom filename template work?: Switch naming mode to custom and enter a token template; the resolved names update live using the same function that generates the actual export, so what you see in the preview list is exactly what you'll download. Leave it on the default mode to just swap each file's extension for the target format's.
Are my images uploaded to convert them?: No. Decoding happens through the browser's own image APIs and re-encoding runs in Web Workers using WebAssembly codec builds, all inside your browser tab. No file, pixel, or filename is sent to a server at any point in the process.
How do I convert WebP to PNG or JPG?: Drop the WebP files into the queue, choose PNG or JPEG under Convert all images to, and press Convert all. Pick PNG if the images have transparent backgrounds, because JPEG cannot store transparency and those areas would be filled in.
Does converting an image reduce its quality?: Converting to PNG, or to WebP or AVIF with lossless switched on, keeps the decoded pixels exactly. Converting to JPEG, or to lossy WebP or AVIF, recompresses the image at the quality you set, so some detail is traded for a smaller file.
Can I convert HEIC photos from an iPhone to JPG?: It depends on your browser. The converter decodes files with the browser's built-in image support and ships no HEIC decoder, so HEIC photos only load in browsers that can already display them; elsewhere, export them as JPEG from the phone first.
Which is better for websites, WebP or AVIF?: AVIF usually produces the smaller file at the same visual quality, while WebP encodes faster and has a longer track record with CMS plugins and image tools. Many sites serve AVIF with a WebP or JPEG fallback to get both benefits.

Related tools on BrakeTools

Image Compressor — Batch-compress images locally, 40 per batch free, with codec choice and a live SSIM preview.
Image Resizer — Resize images by longest edge, exact dimensions or percentage, with letterbox or stretch fitting.
Images ↔ PDF Converter — Combine images into a PDF, or split a PDF back into individual images — either direction, entirely on-device.
SVG Vectorizer — Convert a raster logo into a clean, layered SVG, no subscription required.

Content reviewed 2026-09-27.