AltF Developers
oEmbed provider reference
GET /api/oembed?url=<AltFTool tool URL> returns a standard oEmbed 1.0 "rich" response whose html field is a ready-to-inject iframe of that tool's widget. WordPress, Ghost and other editors that run oEmbed discovery call it for you when someone pastes a tool link on its own line. Your own CMS can call it directly: it is CORS-open, cached and needs no key.
- No API key
- Free, no sign-up
- Real responses, no mock data
- Code in 5 languages
API explorer
Pick an endpoint, set the parameters and send a real request. No key needed.
Turns an AltFTool tool or widget URL into ready-to-inject iframe markup, the way WordPress and Ghost expand pasted links.
Required. Must be an AltFTool page that has a widget, or 404 is returned.
Optional upper bound. The widget shrinks to fit and never grows.
Optional upper bound.
Only json. Anything else returns 501.
GEThttps://www.altftool.com/api/oembedCode for this request
curl -sS -H "Accept: application/json" 'https://www.altftool.com/api/oembed'
Parameters
- url (required): an AltFTool tool, converter or exam-photo page, or its /embed/widget/ URL.
- maxwidth, maxheight (optional): upper bounds in pixels. The widget shrinks to fit and never grows past its natural size (600 x 640 for tools).
- format (optional): only json. Any other value returns 501.
Response and errors
- 200: version, type "rich", provider_name, provider_url, title, author_name, author_url, html, width, height, cache_age 86400.
- 400: the url parameter is missing.
- 404: the URL is not an AltFTool page with a widget.
- 501: a format other than json was requested.
Safety
The url you send is never echoed back. It is resolved to a known widget id, and every field of the response, including html, is rebuilt from that id and AltFTool's own address. That keeps the endpoint from being used to inject markup into the sites that consume it.
Limits, CORS and caching
| Endpoint | Returns | Browser CORS | Rate limit | Cache |
|---|---|---|---|---|
| GET /api/oembed | oEmbed provider | Any origin (Access-Control-Allow-Origin: *) | No per-client limit; cached at the CDN | CDN 1 hour, then stale for up to 24 hours; cache_age 86400 |
Read from each route's source code on 2026-11-01.
oEmbed provider reference: questions and answers
Which editors expand AltFTool links automatically?
Editors that run oEmbed discovery, such as self-hosted WordPress and Ghost. Discourse needs an admin to allowlist altftool.com first. Others can use the iframe snippet instead.
Why do I get a 404?
The page you passed has no widget. Most /tools/all tools, /transform converters and exam-photo pages do; the widget gallery on /embed lists them.
Can I change the widget's size?
Yes, downward. Pass maxwidth and maxheight and the response is clamped to them.
More developer reference
- Free JSON API quickstart (no API key)Call AltFTool's free public JSON API in a minute: no key, no sign-up. Working cURL, JavaScript, Node.js, Python and PHP examples with caching and 429 handling.
- Signals API referenceGET /api/signals returns search-demand signals for tool ideas: query, category, search volume estimate, opportunity score and momentum. Parameters, fields and examples.
- Open data API referenceTwo free open datasets with CORS enabled: Indian exam photo and signature specs, and the AltFTool file converter index. Fields, attribution rules and code.
- Embed free tool widgets on your siteEmbed free AltFTool calculators, converters and generators on your site with one iframe, a responsive wrapper or a WordPress block. Builder, preview and rules.
- Feeds, sitemaps and llms.txtEvery machine-readable AltFTool file: RSS feed, XML sitemap, Google News sitemap, llms.txt, llms-full.txt, ai.txt and robots.txt, with refresh times and uses.
- Rate limits, 429s and cachingAltFTool API rate limits and cache headers per endpoint, what a 429 response contains, and copyable retry-with-backoff code that honours Retry-After.
Free developer tools
Requests and APIs
JSON and data
Built something with it? Get it seen
Credit AltFTool with a normal link to the page you used, then list your own project where developers look. Our backlinks directory sorts free places to submit a site by type and authority.