Transport for Chicago, US
Chicago Transit Authority (CTA)
- Authentication
- API Key
- HTTPS
- No
- CORS
- Unknown
- Category
- Transportation
- Documentation / URL
- http://www.transitchicago.com/developers/
Overview
Transport for Chicago (CTA) provides train/bus data — key-based (an invalid key returns HTTP 200 with errCd 101, verified).
Quick Start
Train positions (replace YOUR_KEY):
curl "http://www.transitchicago.com/api/1.0/ttpositions.aspx?key=YOUR_KEY&rt=Red"<ctatt><tmst>20260825 18:09:27</tmst><errCd>101</errCd><errNm>Invalid API key.</errNm></ctatt>Authentication
- Register at transitchicago.com → API key.
- Send it as the
keyquery parameter.
⚠️ Gotcha (verified): an invalid key returns HTTP 200 with
errCd 101— checkerrCd/errNm.
Rate Limits & Notes
- Key-based with a free tier (check the docs).
- CTA train/bus data.
FAQ
Is Transport for Chicago free? Key-based with a free tier per the docs.
Why 200 with errCd 101?
Invalid keys return 200 + errCd (verified) — check errCd.
What’s the auth style?
key query parameter.
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