RepDB
Can You Use a Free Exercise Dataset Commercially? A 2026 Licensing Guide
Most teams grab a free exercise dataset, ship it, and never read the license. Here's an honest, accurate breakdown of which exercise datasets are actually safe for commercial use in 2026 — public-domain options, restricted APIs, image-provenance traps — and when a licensed dataset is worth paying for.
If you’re building a fitness app, the first thing you need is exercise data — names, muscles, equipment, instructions, and ideally images. The second thing you need, and the thing almost nobody checks until a lawyer or an app-store reviewer asks, is: am I actually allowed to ship this?
I went through this myself building RepDB. So here’s the honest version — not “all free data is illegal, buy mine,” but what each common option actually permits, where the real traps are, and when paying for a licensed dataset is the right call.
Not legal advice. Licenses change. Always read the current license/ToS of any dataset before you ship, and when in doubt, ask a lawyer.
The one-minute answer
| Source | Typical license | Data — commercial use? | The catch |
|---|---|---|---|
| free-exercise-db | Unlicense (public domain) | ✅ data · ⚠️ images | The JSON is clearly Unlicense; the photos trace to an older repo that never explicitly licensed its images — verify before a paid product |
| wrkout/exercises.json | Public domain | ✅ data · ⚠️ images | Older, less structured; same image-provenance question |
| Kaggle “exercise” scrapes | Often unspecified / scraped | ⚠️ Risky | Image provenance unknown — the data being “free” ≠ the images being cleared |
| Hosted exercise APIs (free tiers) | Proprietary ToS / metered | ⚠️ Depends | Redistribution and offline bundling are usually restricted — read the ToS |
| RepDB free tier | Attribution license | ✅ Yes (in-app, with attribution) | 400 exercises, flat 512×512 images only; no redistribution as a dataset, no generative-AI derivation |
| RepDB | Explicit commercial license | ✅ Yes (paid tier) | It costs money — that’s the trade for a clear license + support |
Short version: genuinely public-domain exercise data exists and you can ship it commercially — but check the images separately; that’s where the risk hides. The decision isn’t “free vs legal” — it’s whether the free option’s hidden costs (below) are cheaper than a licensed one for your product.
”Free” that’s genuinely free
Some open datasets — like free-exercise-db and the older wrkout/exercises.json — release their code and JSON data into the public domain (Unlicense). For the text layer that’s as clean as it gets: use it commercially. The images deserve one extra look, though: free-exercise-db’s photos trace back to the older wrkout repo, which never explicitly licensed its images — the maintainer can dedicate his own work to the public domain, but whether the upstream photos were his to dedicate is an open question. For a hobby project, fine; for a paid product, check the chain of title.
What you’re also trading away is everything around the license:
- Inconsistent images. Public-domain image sets are stitched from different sources, so styles, framing, and backgrounds don’t match. It shows the moment you put them in a grid.
- Coverage gaps. Missing variations, missing equipment, missing the long tail.
- English only. No DE/ES (or anything) out of the box.
- No updates, no one to email. It’s a snapshot. If something’s wrong, you fix it yourself.
For a side project that’s completely fine. For a product you’re charging for, those gaps become your engineering backlog.
”Free” that isn’t quite free
Two categories quietly get teams into trouble:
Commercial APIs with a free tier. Several exercise APIs let you call them for free but their Terms restrict redistributing or bundling the data offline — which is exactly what you do when you ship an app. The data being reachable isn’t the same as it being licensed for your product. Read the ToS for the words “redistribute,” “derivative,” and “cache.”
Scraped datasets (often on Kaggle/GitHub). A dataset can be posted “free” while the images inside it were scraped from a source that never licensed them. The text might be fine; the images can be a copyright claim waiting to happen. If a dataset can’t tell you where its images came from, treat that as a risk — especially for the images, which are the part most likely to be someone else’s IP.
This is the trap that matters most: “the dataset is free” and “the images are cleared for commercial use” are two different statements. Verify the second one.
When a licensed dataset is worth paying for
Pay for a licensed exercise dataset when one or more of these is true:
- You’re shipping a commercial product and want a single, explicit commercial license you can point a reviewer or investor at.
- You need consistent, original illustrations — same style across every exercise — and ideally transparent backgrounds that drop onto any UI.
- You need more than English (DE/ES or beyond).
- You want provenance you can trust — images that were generated/cleared for commercial use, not scraped.
- You’d rather buy the backlog (translations, consistent images, relations/progressions, packaging and QA) than build it.
That’s the gap RepDB fills. It’s a curated, commercial-safe exercise dataset: 455 fully illustrated exercises, two image styles (classic transparent + flat), EN/DE/ES, delivered as JSON + SQLite + WebP — one payment, no API, no rate limits, with an explicit commercial license.
Try before you decide
You don’t have to take my word for it — the data shape and image quality are the whole point, so look first:
- Free tier — 400 exercises (attribution license, commercial in-app use allowed): download it from GitHub — flat 512×512 WebP, the resolution ExerciseDB charges $299 for — or browse the data on GitHub / the live viewer.
- Full dataset & licensing: pricing.
- Still comparing options? See ExerciseDB Alternatives in 2026 for a side-by-side of the datasets themselves.
If a public-domain set covers your needs, use it with a clear conscience. If it doesn’t, now you know exactly what you’re paying for — and what to check before you ship either way.