TypeIDs are now the default identifier format

Every ID in Buttondown's API is a UUID (e.g., 550e8400-e29b-41d4-a716-446655440000) with no indication of what it represents. UUIDs are great for databases, but they're not human-friendly.

Starting with API version 2026-01-01, we're introducing TypeIDs in Buttondown.

A TypeID is a UUID with a readable type prefix. Prefixes like sub_, em_, and tag_ make it immediately clear what kind of object an ID represents, such as sub_ for subscribers, em_ for emails, and tag_ for tags.

Here's what changes in the response:

  Old response (< 2026-01-01)          New response (>= 2026-01-01)
  ───────────────────────────          ────────────────────────────
  {                                    {
    "id": "550e8400-e29b-41d4-...",      "id": "sub_550e8400e29b41d4...",
    "email_id": "7c9e6679-7425-..."      "email_id": "em_7c9e6679-7425..."
  }                                    }

No breaking changes to how you send requests. The API accepts both TypeIDs and UUIDs as input, but responses are version-aware. Send a request with X-API-Version: 2026-01-01 and you'll always get TypeIDs back, regardless of what format you sent in.

curl "https://api.buttondown.com/v1/subscribers" \
  -H "Authorization: Token YOUR_API_KEY" \
  -H "X-API-Version: 2026-01-01"

This is now the default version for every new API key. If you are using an older API version (< 2026-01-01), nothing changes — your API responses still continue to contain UUIDs exactly as they are. But if you want to use our latest TypeID system, migrate through the dashboard or pass X-API-Version: 2026-01-01 in your request headers.