Public Health API Practice Sandbox

Phase 1 — no login required Phase 2 — API key required

This is a practice API built for the "Building Practical API Workflows for Public Health" workshops. It behaves like a real public-health data API — you'll ask it questions and it will hand back data — but everything here is safe to experiment on and won't break anything.

The one thing you need to know: the base URL

https://test-api.seminars.page

Everything you do starts by adding something to the end of this address.

What data is available

There are two "resources" — think of each as a table you can ask questions of:

Getting a key: the credential step (Advanced workshop)

Both resources now require you to prove you're allowed to ask for data. This happens in two steps, and it mirrors how most real public-health APIs work:

1. You were given a classroom API key — a shared password for this workshop, distributed by your facilitator. Think of it like a house key: it works, but if it's lost or shared too widely, everyone in the house has to get new keys.
2. You exchange that key for a temporary token — think of this like a bus ticket: it only works for a little while, and if you lose it, only that one ticket needs replacing, not the whole house's locks.

Step 1 — exchange your classroom key for a token

POST https://test-api.seminars.page/v1/token
Header: X-API-Key: YOUR-CLASSROOM-KEY

Response:

{
  "token": "3F82ac9K...",
  "token_type": "Bearer",
  "expires_in": 900
}

expires_in is in seconds — this token stops working after 15 minutes, and you'll need to repeat this step to get a new one. That's deliberate: it's the whole point of the "temporary credential" concept.

Step 2 — use the token on every request

Add it as a header on /v1/cases and /v1/immunizations requests:

GET https://test-api.seminars.page/v1/cases?state=CA&limit=25
Header: Authorization: Bearer 3F82ac9K...

Doing this in Excel Power Query

1. Data → Get Data → From Other Sources → From Web
2. Choose Advanced (not Basic) so you can add headers
3. For the token step: set the URL to https://test-api.seminars.page/v1/token, and under "HTTP request header parameters" add X-API-Key with your classroom key. You'll need to switch the request to POST — Power Query's "From Web" dialog exposes this under its advanced options.
4. Copy the token value out of the response
5. For each data request: set the URL to /v1/cases or /v1/immunizations as before, and add a header named Authorization with the value Bearer followed by your token (note the space after "Bearer")

Example request — Cases

https://test-api.seminars.page/v1/cases?state=CA&limit=25

This asks for up to 25 case records from California. Here's what comes back:

{
  "data": [
    {
      "id": 1,
      "state": "CA",
      "county": "Los Angeles",
      "report_date": "2026-06-01",
      "case_type": "influenza-like illness",
      "case_count": 12
    }
  ],
  "next_cursor": "MjU=",
  "count": 25
}

Parameters you can use

Example request — Immunizations

https://test-api.seminars.page/v1/immunizations?county=King&limit=25

Pagination — why you sometimes need a "second page"

This API deliberately never hands you an entire dataset in one response, even if the whole thing would technically fit. Real public-health APIs work the same way, both to protect their servers and because most tools (Excel included) work better with data in manageable chunks.

Every response includes a next_cursor value. If it's a piece of text, there's more data waiting — take that value and add it to your address as &cursor=THAT_VALUE to get the next page. If next_cursor is null, you've reached the end.

https://test-api.seminars.page/v1/cases?state=CA&limit=25&cursor=MjU=

Rate limiting — why you might get slowed down

Each token can make up to 20 requests per minute. If you go over that, you'll get an error back instead of data, with a hint about how long to wait:

HTTP 429 Too Many Requests
Retry-After: 37

{
  "error": {
    "code": "RATE_LIMITED",
    "message": "Too many requests. Try again in 37 seconds."
  }
}

This is normal, and it's there on purpose — real APIs do this to stay reliable for everyone using them. Retry-After tells you how many seconds to wait before trying again.

A data-quality note worth watching for

Errors you might see