API

The fckurl public API exposes a single endpoint: link creation. Everything else (listing, deletion, rotation, custom domains, API keys) is managed from your dashboard.

Create a link

curl -X POST https://fckurl.com/api/v1/links \
  -H "Content-Type: application/json" \
  -d '{"url":"https://example.com/some/long/url"}'

Response (201 Created):

{
  "id": 42,
  "code": "G",
  "shortUrl": "https://fckurl.com/G",
  "targetUrl": "https://example.com/some/long/url",
  "strategy": "Sequential",
  "createdAtUtc": "2026-04-27T12:34:56Z",
  "secret": null
}

Request fields

• url (required) — the destination, absolute http(s).
• slug (optional) — custom code matching [A-Za-z0-9_-]{1,32}. Requires an API key.
• mode (optional) — sequential (default, compact base62 code) or two_key (random code + secret returned exactly once; URL becomes /code/secret).
• domain (optional) — a verified custom domain you own. Requires an API key.

Authentication

Anonymous requests can create links on the platform domain. An API key is only required when you supply slug or domain:

X-Api-Key: fck_<prefix>_<secret>

Issue keys from the dashboard. Each key is shown exactly once.

Status codes

• 201 Created — link created. two_key responses include secret exactly once.
• 400 Bad Request — malformed URL, invalid slug, unknown domain.
• 401 Unauthorized — API key required for the requested options.
• 409 Conflict — slug already taken on this domain.