Circle Signing API

openapi: 3.1.0
info:
  title: Circle Web3 Services (W3S) — Developer-Controlled Wallets NFTs Signing API
  description: 'Circle''s Web3 Services API for developer-controlled programmable wallets, wallet sets,

    signing, transactions, tokens, and NFTs. This is a best-effort partial spec derived

    from Circle''s published OpenAPI at

    https://developers.circle.com/openapi/developer-controlled-wallets.yaml.'
  version: '2026-05-23'
  contact:
    name: Circle Developer Support
    url: https://developers.circle.com/
  license:
    name: Proprietary
servers:
- url: https://api.circle.com
  description: Production
security:
- BearerAuth: []
tags:
- name: Signing
paths:
  /v1/w3s/developer/sign/message:
    post:
      tags:
      - Signing
      summary: Sign a message
      operationId: signMessage
      responses:
        '200':
          description: Signature
  /v1/w3s/developer/sign/typedData:
    post:
      tags:
      - Signing
      summary: Sign EIP-712 typed data
      operationId: signTypedData
      responses:
        '200':
          description: Signature
  /v1/w3s/developer/sign/transaction:
    post:
      tags:
      - Signing
      summary: Sign a transaction
      operationId: signTransaction
      responses:
        '200':
          description: Signature
  /v1/w3s/developer/sign/delegateAction:
    post:
      tags:
      - Signing
      summary: Sign a delegate action
      operationId: signDelegateAction
      responses:
        '200':
          description: Signature
components:
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer
      description: Circle API key, formatted as `PREFIX:ID:SECRET`, supplied as Bearer token.