For developers, journalists and researchers
Free data API
Everything rendered on this site is also a JSON file. No key, no sign-up, no rate limit, no analytics on the endpoints. If you need a rate figure you can cite, take it straight from here.
Endpoints
| Path | Returns |
|---|---|
/data/index.json | Catalog of every series and derived figure, with latest values |
/data/series/<slug>.json | Full history for one series, with provenance |
/data/derived/<slug>.json | A computed spread, with its inputs named |
/data/current.json | Latest value for every active series |
/data/events.json | Detected movements, newest first |
/data/sources.json | Every source, with required citations |
/data/exportable.json | Which series may be redistributed in bulk |
Shape
Observations are [date, value] pairs, oldest first — about a third the bytes of objects on a nine-thousand-point series. Every file carries built_at, and every series carries a provenance block naming its source, terms, and required citation.
What you may redistribute
253 of 272 series are public-sector data — reuse them freely, including commercially. A link back is appreciated so your readers can check the provenance, but it is not a condition.
19 series are third-party copyrighted (Optimal Blue and Freddie Mac). We publish them under their citation requirement, which permits publication but not onward redistribution. They are excluded from exportable.json by the database itself rather than by a note in a document — so a bulk export cannot include them by accident. If you need those figures, take them from the original providers.
Stability
Slugs are permanent once published; they are URLs, and we treat them as a contract. Files carry api_version. A breaking change would ship under a new version rather than mutating the existing one, and would be recorded on the changelog.
Data is rebuilt once daily. Please cache rather than polling — there is nothing newer to find between builds, and the whole catalog is one request.
Citing us
A figure is only as good as its provenance, so please cite the original source rather than us — every file names it. If our derivation is the thing you are using (a spread, a ranking, a comparison), cite The Rate Engine and link the page, so readers can see how it was computed.