IUCN Red List of Threatened Species
Last verified: April 1, 2026
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?api_key=YOUR_KEY) or in the request header (Authorization: Bearer YOUR_KEY). Check the API's documentation for the exact format.API keys are free for most public APIs. They're used to identify your application and enforce rate limits — not to charge you.
This API does not support CORS, so you'll need to call it from a server-side application or use a proxy. Direct browser requests will be blocked by the browser's same-origin policy.
IUCN is a free API in the Animals category. It requires a free API key, which you can obtain by signing up on their website. This API does not require HTTPS and does not support CORS — you will need to call it from a server-side application.
IUCN fits naturally into projects that touch the Animals space. Here are a few directions developers commonly take when working with APIs in this category — any of them could be a fit depending on the specific endpoints IUCN exposes:
If a specific use case isn't listed, scroll back to the code examples above and adapt the request shape to match the endpoint you need. Most Animals APIs follow similar request/response patterns, so the snippet that works for one endpoint usually works for the rest with small tweaks.
1. Skim the documentation first. Open the link above and look for two things: the base URL pattern and a list of available endpoints. Knowing both up front saves you from guessing parameter names or formats. Most providers also publish example responses next to each endpoint — copy one into your editor as a reference for the JSON shape your code will be parsing.
2. Get an API key. IUCN uses API key authentication. Sign up on the provider's site, look for a developer dashboard or API section in your account settings, and copy your key somewhere safe. Treat it like a password — don't paste it into a public repo or a client-side bundle that ships to a browser. Read our API security guide if you're unsure how to keep keys out of source control.
3. Make a request from the command line. Before wiring an API into your application, send a single request with curl or your HTTP client of choice. Confirm that the response shape matches what the docs promised. If it doesn't, your application code would have hit the same surprise — better to find out now while you only have one terminal window to debug.
4. Wire it into your code. Once a manual request works, copy that request into your application as a function. Add error handling: APIs return 4xx and 5xx codes for client and server errors respectively, and your code needs to behave reasonably when one comes back. Our error-handling guide covers the patterns that make this less painful.
5. Don't call it directly from the browser. IUCN doesn't support CORS, so a browser-side fetch() will be blocked by the same-origin policy. Call it from your backend instead and forward the result to the frontend. If you don't have a backend, a serverless function (Cloudflare Workers, Netlify Functions, Vercel) is a quick way to add one.
Heads up: HTTPS. IUCN is listed as not requiring HTTPS, which is unusual for modern APIs. If your application runs on an HTTPS-served page, browsers will block plaintext requests as mixed content. Either run your code from a non-HTTPS host (locally is fine) or look for an HTTPS variant of the same API in our directory.
Authorization header, or a custom header — every provider does it slightly differently. The official docs will say which.curl but not in your app: almost always a header-encoding bug. Print the exact request your client sends and compare it to your working curl command. Look for missing quotes, extra spaces, or a header name typo.Animal APIs provide fun and educational data about pets, wildlife, and everything in between. Whether you want random cat photos for your app or detailed breed information for a pet adoption site, these APIs deliver animal content on demand.
IUCN is one of dozens of free Animals APIs we've catalogued. Some are nearly interchangeable; others have distinct strengths and weaknesses that only become clear when you read their docs side-by-side. If IUCN doesn't quite fit your project, the Animals category page lists every alternative we know about, with auth and CORS columns so you can compare at a glance.
When evaluating Animals APIs, the criteria that matter most are typically: rate limits on the free tier, freshness of the underlying data, regional coverage (does it work for your users' geography?), and how active the provider's maintenance schedule is. APIs that haven't been updated in years tend to drift out of sync with the underlying data sources, even if they technically still respond.
IUCN is an animal API that may provide species information, animal images, breed data, wildlife facts, or conservation status. Some animal APIs focus on specific types (dogs, cats, birds) while others cover the entire animal kingdom. Check the documentation for available data fields.
Many animal APIs offer random image endpoints that return photos of animals — popular for testing, placeholders, or fun apps. IUCN may include image URLs in its responses. Check the API endpoints to see if image delivery is supported and what formats are available.
Some animal APIs provide detailed taxonomic or breed information including physical characteristics, temperament, lifespan, and habitat. Whether IUCN offers this depends on its scope. For more animal data sources, browse our Animals APIs.
Yes, IUCN is listed as a free public API. You will need to create a free account to get an API key, but the key itself is free. Some APIs have rate limits on their free tier, so check the official documentation for current limits.
Yes! According to our most recent health check (IUCN's last ping: 2026-04-01 13:37:45), this API is responding normally. We periodically verify all listed APIs to ensure they are still online and functioning.