Overview
ITIS (Integrated Taxonomic Information System) is a free API providing authoritative taxonomic data on plants, animals, fungi, and microbes. You can look up the official scientific classification of any organism by name, Taxonomic Serial Number (TSN), or common name. It is maintained by US government agencies and is highly reliable for biodiversity and biology projects.
Beginner Tip
Search by common name first using the searchByCommonName endpoint to find the TSN, then use that TSN to retrieve full hierarchical classification. All responses are available in JSON by using the /jsonservice/ path in the URL.
Measurement Record
What actually happened when we called this API from our own infrastructure. Every value below was recorded by the request, not copied from the provider's documentation.
- Request
- GET https://www.itis.gov/ITISWebService/jsonservice/searchByCommonName?srchKey=bald+eagle
- Result
- HTTP 200 · text/json · 209 bytes
- Response time
- 579 ms (median of 3) · fastest 551 ms
- Transport
- TLSv1.3 · TLS_AES_256_GCM_SHA384 · certificate issued by Internet2
- Browser CORS
- No Access-Control-Allow-Origin header — call it from a server, not the browser
- Recorded
- 2026-08-10
Fields Returned
Top-level fields present in the response we captured, with the type and value we actually received.
| Field | Type | Value received |
|---|---|---|
| class | string | gov.usgs.itis.itis_service.data.SvcCommonName… |
| commonNames | array | [1 item] |
| tsn | null | null |
Captured Response
Captured from a real request to https://www.itis.gov/ITISWebService/jsonservice/searchByCommonName?srchKey=bald+eagle on 2026-08-10. Long arrays and nested objects are truncated to keep the shape readable.
{
"class": "gov.usgs.itis.itis_service.data.SvcCommonNameList",
"commonNames": [
{
"class": "gov.usgs.itis.itis_service.data.SvcCommonName",
"commonName": "Bald Eagle",
"language": "English",
"tsn": "175420"
}
],
"tsn": null
} Field Reference
tsn Taxonomic Serial Number — the unique ITIS identifier for a taxon. commonNames List of common name objects with name and language. Implementation Example
Calls a real endpoint of this API. Replace any placeholder credentials with your own key.
const url = "https://www.itis.gov/";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data); What Can You Build?
Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.
How This API Fails
We deliberately sent this API a broken request and recorded exactly what came back on 2026-08-10. Knowing the shape of an error before you hit it makes error handling much easier to write.
Returned an HTML error page rather than JSON — worth knowing if your client assumes every response can be parsed as JSON.
Common Errors & Troubleshooting
Generated guidance based on this API's documentation, not observed by us. Treat it as a starting point and check against the provider's own error reference.
Measured Score Breakdown
Live HTTP request to the API endpoint
Fully tested on Aug 10, 2026
Technical Specifications
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