Public API

The public REST API lets scripts and apps create SayDiagram diagrams from a text idea or an image. Keys are available on Pro and Team (including Team members who inherit Pro quotas). Create and revoke keys in Profile → API keys.

Base URL: https://saydiagram.com/api/v1

Pass your secret with Authorization: Bearer sd_live_… or the X-Api-Key header. The secret is shown once when you create a key; we store only a hash.

curl -s https://saydiagram.com/api/v1/me \
  -H "Authorization: Bearer sd_live_YOUR_SECRET"

POST /api/v1/diagrams/from-idea with JSON { idea, diagramType?, folderId? }. Returns a saved diagram DTO including editorUrl. Counts against your daily idea quota (same as the web app).

curl -s -X POST https://saydiagram.com/api/v1/diagrams/from-idea \
  -H "Authorization: Bearer sd_live_YOUR_SECRET" \
  -H "Content-Type: application/json" \
  -d '{"idea":"User signs up, verifies email, then lands on dashboard","diagramType":"flowchart"}'

POST /api/v1/diagrams/from-image as multipart file=… or JSON { imageBase64, mimeType?, filename?, folderId? }. PNG, JPEG, or WebP up to 4MB. Counts against your daily image-scan quota.

curl -s -X POST https://saydiagram.com/api/v1/diagrams/from-image \
  -H "Authorization: Bearer sd_live_YOUR_SECRET" \
  -F "file=@whiteboard.png"

• 401 API_KEY_INVALID — missing, revoked, or wrong key
• 403 API_KEY_PLAN_REQUIRED — Free plan (upgrade to Pro or Team)
• 403 IDEA_GENERATE_DAILY_LIMIT / IMAGE_SCAN_DAILY_LIMIT — daily quota used
• 429 AI_RATE_LIMIT — too many AI requests (per-user soft limit)

GET /api/v1/me returns plan and remaining idea/scan/layout usage for the UTC day.

Machine-readable entry points: https://saydiagram.com/llms.txt (index), https://saydiagram.com/llms-full.txt (full playbook), https://saydiagram.com/openapi.json (OpenAPI 3.1). Human agent guide: https://saydiagram.com/doc/agents.