SlicePost API & MCP

Quick start

Create a key in Account → Developer access → API keys. The secret is shown once. Store it as SLICEPOST_API_KEY in your client environment.

curl https://www.slicepost.com/api/projects \
  -H "Authorization: Bearer $SLICEPOST_API_KEY"

Keys, expiry, and permissions

Every API and MCP call uses a personal sp_beta_… bearer key. In Account, name each client key, choose a 30, 90, or 365 day expiry, and grant only the scopes it needs. You can create multiple keys; the list loads 50 at a time. Keys inherit the creator's approved workspace and stop when revoked, expired, or removed from beta.

For rotation, create a replacement, update your client, verify a read request, then revoke the old key. Lost secrets cannot be retrieved.

Permissions

From source to finished output

The API uses the same workspace ownership, private media, allowances, and durable job queue as the dashboard. Upload completion never starts paid work.

1. Create a projectPOST /api/projects with tool_type and a name.
2. Upload privatelyReserve with filename, exact byte size, and a stable key. Transfer raw bytes using the signed ticket, then complete.
3. Validate the sourceQueue validation and poll the returned job. Read trusted duration, FPS, geometry, and codecs.
4. Quote and queueReview the allowance impact, then send a stable Idempotency-Key for chargeable work.
5. Poll statusA 202 response is accepted work. Poll its request until complete and inspect published assets.

Signed upload URLs are short lived and private. If a transfer or request is interrupted, inspect its current state and reuse the same operation key before starting another.

Choose a workflow

Read request fields, endpoint paths, and response flow in the complete Markdown reference →

Connect your AI client

Use the same key as REST. Set SLICEPOST_API_KEY in the environment of the process that launches your client, add the configuration, then reconnect the client. Account → MCP connection has these snippets beside your key list.

[mcp_servers.slicepost]
url = "https://www.slicepost.com/mcp/"
bearer_token_env_var = "SLICEPOST_API_KEY"

{
  "mcpServers": {
    "slicepost": {
      "type": "http",
      "url": "https://www.slicepost.com/mcp/",
      "headers": {
        "Authorization": "Bearer ${SLICEPOST_API_KEY}"
      }
    }
  }
}

The MCP URL ends in /mcp/. The Claude Code example belongs in a project .mcp.json and keeps the key in your environment. The client must support Streamable HTTP and bearer headers. The MCP tools coordinate jobs; your client still transfers media bytes using the returned signed upload instructions.

What agents can do

Available processing depends on your beta workspace. Quote first, confirm chargeable work with the user, reuse an idempotency key on retry, and poll status before presenting an output as complete. See every tool name and workflow →

Credits follow the work, not the client.

Dashboard, REST, and MCP share one workspace balance. Clipping charges complete analyzed source minutes, rounded down. Caption Maker and optional editor transcription use caption/transcription minutes. Initial AI outputs and later edits or rerenders are included.

Errors, retries, and rate limits

Clipping, Caption Maker, and editor rerender queues require an Idempotency-Key header; uploads and standalone editor creation use a body key. Reuse the same key after a lost response to avoid duplicate work.

Connection checklist

1. No MCP toolsCheck the /mcp/ URL, client environment, and reconnect the client.
2. Authentication errorCheck the bearer key, expiry, and revocation status. Replace a lost key in Account.
3. Permission errorCreate a replacement key with the needed scope, switch your client, then revoke the old key.
4. Missing resourceVerify the ID and workspace. A cross-workspace resource deliberately returns 404.
5. Interrupted jobRead its current state, honor Retry-After, and reuse the same idempotency key.

Share the X-SlicePost-Request-ID with support; keep the key and signed media URL private.

Current beta boundaries

• Only approved beta accounts can create or use keys.
• Sources are capped at 10 GB and five hours; Clipping requires at least three minutes.
• Remote OAuth is a later launch boundary; beta clients use revocable personal keys.
• Social publishing and billing remain human-only.
• Feature flags can disable processing surfaces independently without exposing partial workflows.