Smolr vs Smol: Two Different Mac Apps, One Letter Apart

Most casual users should install Smolr and stop there. Four situations where it is not just acceptable but correct.

Your files are images and your budget is zero. Smolr optimizes JPEG, PNG, GIF, WebP, AVIF and JXL, converts between WebP, AVIF, JXL, PNG and JPEG, takes a whole folder by drag and drop, strips EXIF, and saves next to the original with a _smolr suffix. That covers the overwhelming majority of “this photo is too big” problems. Paying $29 to solve a problem a free app already solves is not a trade we are going to argue for.

You want JPEG XL. Smol does not output JXL. Smolr does, through a bundled build of the libjxl reference implementation. If you are testing JXL for an archive or a research pipeline, that alone decides it.

You are on an Intel Mac and want one binary. Smolr ships a single universal build covering Apple Silicon and Intel, with all encoders bundled as universal binaries. Smol has separate Apple Silicon and Intel downloads, and the Intel build needs macOS 14 where Smolr needs the same. Functionally close, but one download is simpler than choosing.

You want to read the code before you run it. This is the argument we cannot answer. Smolr is BSD 3-Clause with the full Xcode project on GitHub and every third-party encoder credited: libwebp, libavif, libjxl, MozJPEG, oxipng, pngquant and Gifsicle. Its own FAQ puts it well: “Because transparency matters. You can inspect the code, understand what the app does, and trust that nothing hidden is happening in the background.” Smol is closed source. We can tell you what it does; we cannot show you.

One practical note in both directions. Smolr is not code-signed, so the first launch is blocked by Gatekeeper and you have to approve it in System Settings → Privacy & Security. The README walks through it step by step. That is normal for an unfunded open-source Mac app and it is not a security red flag by itself, but it is a hurdle, and on a managed work Mac it may simply not be possible.

One letter, two unrelated projects. Here is the fastest way to tell which one you have.

If the app in your Applications folder is called Smolr.app and macOS refused to open it the first time, you have Smolr. If it is called Smol.app and it asked you for a licence key, you have ours.

One more that catches developers: Hugging Face publishes smolagents, an Apache-2.0 Python library for building code-writing agents with roughly 29,500 stars on GitHub. It is a machine-learning library and has nothing to do with either Mac app. “Smol” is a crowded word.

Drop images or a folder in, pick a target format from the picker at the bottom or leave it on Original, move the quality slider, press ⌘ Return. Files land next to the originals with a configurable suffix. That is the whole interaction, and the app is better for it.

The format story is specific and worth getting right, because the README draws a line most write-ups miss. Optimization works on PNG, JPEG, GIF, WebP, AVIF and JXL, keeping the format and just squeezing. Conversion targets are WebP, AVIF, JXL, PNG and JPEG. GIF is optimize-only: you can shrink a GIF you already have, but you cannot turn something else into one. By default the picker shows Original, WebP, AVIF and JXL, with PNG and JPEG available once you enable them in settings.

The four optimization profiles are the most interesting thing in the app, and the README is refreshingly blunt about the cost. Fast, Balanced, Quality and Size tune how hard each encoder works, and it states that Quality and Size “can be 10–20× slower than Fast, especially on large files.” The 50–100% quality slider applies on top of whichever profile you pick. Most apps hide that tradeoff behind a vague “better compression” toggle. Smolr tells you it will take twenty times longer.

Everything runs locally. Nothing is uploaded, there is no account, and the privacy policy at smolr.io says the site collects nothing from visitors. Payments, if you choose to make one, go through Payhip or PayPal.

Release history, for anyone weighing it: six releases between v1.0.0 on 20 January 2026 and v1.1.1 on 20 February 2026, with the most recent commit on main dated the same day. It has not shipped since. That is not evidence of abandonment, and we are not going to imply otherwise. A small tool with a single job can be finished. It does mean that if a format you need is missing today, waiting is not a strategy. The repo has five stars, and its AlternativeTo listing, added 26 January 2026, has no votes on it yet. It is a small project that deserves more attention than it has.

Four walls, in rough order of how often people hit them.

HEIC. This is the big one on a Mac. Smolr’s supported list is JPEG, PNG, GIF, WebP, AVIF and JXL. HEIC is not on it, which means the default format of every photo taken on an iPhone since 2017 will not open. If your camera roll is the reason you went looking for a compressor, Smolr cannot help and no setting changes that. Smol treats HEIC as both an input and an output, and reads RAW from Canon, Nikon, Sony and Adobe cameras as well.

Anything that is not an image. No PDF, no video, no audio, no Office files. That is by design and the site says so. The moment a job is “this client folder has 40 photos, a 200 MB screen recording and three PDFs,” it becomes two or three apps. Smol compresses PDFs with five presets, video to MP4, MOV, WebM and MKV, and audio to AAC, M4A, MP3, WAV, FLAC, OGG and Opus, and converts Word, spreadsheet, presentation, table and font formats in the same window.

Resizing and exact sizes. Smolr has no resize control. Quality goes down to 50% and that is the only lever. If an upload form caps you at 2 MB, or a CMS wants a 2,000 px maximum edge, you need another tool in the chain. Smol resizes with fit, fill, width or height up to 32,768 px, and its neural mode takes a target in kilobytes anywhere from 4 to 4096 and encodes to hit it.

Hands-off work. Smolr is a window you open. There are no watched folders, no Finder Quick Action, no clipboard hotkey. For ten images a week that is fine. For a screenshots folder that fills up every day, the app you have to remember to open is the app you stop using. Smol can watch a folder and compress anything that lands in it, sits in the Finder right-click menu, and compresses whatever is on the clipboard.

There is a fifth wall that only applies to a few readers, and it is the reason some people buy Smol at all. Smol ships an MCP server, so Claude Code, Codex or Google Antigravity can call compression, conversion, upscaling and metadata stripping as tools inside a task. “Convert every PNG in public/ to WebP under 150 KB, then rerun the build” becomes something the agent does rather than something you do afterwards. Smolr has no scripting interface of any kind, not even a CLI.

Try Smolr first. It is free, it is 30 seconds to test, and if it does the job you have saved $29 and learned something about what you actually need. That advice is not reverse psychology, it is what the honest answer looks like when the other tool is free and competent.

Buy Smol when you have hit one of the four walls above and know which one. The usual trigger is HEIC or PDFs. The second most common is realizing that the work is recurring, at which point a watched folder stops being a feature and starts being the point.

If you are still gathering options, three neighbouring pages are written the same way as this one. Smol vs Dinky covers the other free open-source Mac compressor, which is broader than Smolr and also handles video, audio and PDFs. Squoosh alternatives covers the browser tool that Google stopped maintaining in 2024. ImageOptim alternatives covers the free lossless route, and Optimage alternatives documents a paid Mac compressor that has not shipped since 2021 and is still Intel-only.

If the answer is ours, Smol is a one-time $29 purchase covering one Mac, with no subscription, no per-file limits and no upload queue.