Circle

Circle Internet Financial is the issuer of USDC and EURC and operates a developer platform for moving regulated stablecoin money across the internet. Their APIs cover programmable wallets (developer- and user-controlled), gas sponsorship, the Cross-Chain Transfer Protocol (CCTP), Gateway unified balances, the Smart Contract Platform, the Circle Payments Network (CPN) for cross-border payments, compliance, StableFX trading on Arc, and xReserve for issuing USDC-backed stablecoins.

Circle publishes 6 APIs on the APIs.io network, including NFTs API, Signing API, Tokens API, and 3 more. Tagged areas include Blockchain, Compliance, Cross-Chain, Currency, and Money.

The Circle catalog on APIs.io includes 1 event-driven AsyncAPI specification, 1 JSON-LD context, and 3 Spectral governance rulesets.

Circle’s developer surface includes API reference, authentication, developer portal, developer console, getting-started guide, support, engineering blog, and 18 more developer resources.

🌐 Visit website 📡 Source on GitHub

42.0/100 developing ▬ flat Agent 30/100 agent ready saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

AccessFreemiumSelf serve⚡ Free to try

1 APIs 1 MCP Servers

Blockchain Compliance Cross-Chain Currency Money Payments Stablecoins Transfers USDC Wallets

Kin Score

Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0

Composite quality — 42.0/100 · developing

Contract Quality 11.5 / 19

Developer Ergonomics 7.1 / 15

Access Clarity 3.9 / 15

Operational Transparency 2.6 / 10

Contract Governance 1.2 / 9

Discoverability 5.7 / 8

Regulatory Posture 4.9 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 30/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 6 / 6

MCP Server 12 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Payments regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/circle: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 7

Individual APIs this provider publishes, each with its own machine-readable definition.

Gas Station and Paymaster

Sponsor gas fees on behalf of users or let users pay gas in USDC via Circle Paymaster, removing native-token friction from onboarding.

Circle NFTs API

The NFTs API from Circle — 1 operation(s) for nfts.

Circle Signing API

The Signing API from Circle — 4 operation(s) for signing.

Circle Tokens API

The Tokens API from Circle — 1 operation(s) for tokens.

Circle Transactions API

The Transactions API from Circle — 12 operation(s) for transactions.

Circle Wallet Sets API

The Wallet Sets API from Circle — 4 operation(s) for wallet sets.

Circle Wallets API

The Wallets API from Circle — 7 operation(s) for wallets.

Scroll for all 7

Open Collections 8

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

Circle Web3 Services (W3S) — Developer-Controlled Wallets NFTs API

OPEN COLLECTION

Circle Web3 Services (W3S) — Developer-Controlled Wallets NFTs Signing API

OPEN COLLECTION

Circle Web3 Services (W3S) — Developer-Controlled Wallets NFTs Tokens API

OPEN COLLECTION

Circle Web3 Services (W3S) — Developer-Controlled Wallets NFTs Transactions API

OPEN COLLECTION

Circle Web3 Services (W3S) — Developer-Controlled Wallets NFTs Wallet Sets API

OPEN COLLECTION

Circle Web3 Services (W3S) — Developer-Controlled NFTs Wallets API

OPEN COLLECTION

Circle Web3 Services (W3S) — Developer-Controlled Wallets API

OPEN COLLECTION

Scroll for all 8

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

Circle MCP Server

MCP SERVER

Pricing Plans 1

Published pricing tiers and plan structures.

Circle Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Circle Rate Limits

5 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Circle Finops

FINOPS

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Circle Webhook Notifications

AsyncAPI description of Circle's outbound webhook (notification) surfaces. Circle delivers event notifications by POSTing a JSON body to a subscriber endpoint that is registered...

ASYNCAPI

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Circle Context

0 classes · 6 properties

JSON-LD

Spectral Rules 3

Spectral governance rulesets for linting and validating these APIs.

Circle API Rules

8 rules · 1 errors 7 warnings

SPECTRAL

Circle API Rules

5 rules · 3 warnings 2 info

SPECTRAL

Circle API Rules

9 rules · 4 errors 4 warnings 1 info

SPECTRAL

JSON Schema 2

Standalone JSON Schema definitions for this provider's data models.

Circle Transaction

17 properties

JSON SCHEMA

Circle Wallet

11 properties

JSON SCHEMA

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Circle Authentication

http · 1 scheme

SECURITY

Circle Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Circle Agentic Access

30 operations · 18 acting · 3 human-in-the-loop

30 operations · 18 acting

AGENTIC

Resources

Get Started 3

Portal, sign-up, and the first successful call

Portal

Portal

Console

Console

GettingStarted

GettingStarted

Documentation 4

Reference material describing how the API behaves

APIReference

JSONSchema

JSONSchema

AsyncAPI

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

AgentSkills

MCPServer

AgenticAccess

LlmsText

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

JSONLD

JSONLD

Spectral

Spectral

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 3

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Authentication

Authentication

Operate 3

Status, limits, changes, and where to get help

StatusPage

StatusPage

Support

Support

Community

Community

Commercial 2

Pricing, plans, and the legal terms of use

PrivacyPolicy

PrivacyPolicy

TermsOfService

TermsOfService

Company 3

The organization behind the API

LinkedIn

Website

Website

Blog

Blog

Source (apis.yml)

aid: circle
name: Circle
url: https://raw.githubusercontent.com/api-evangelist/circle/refs/heads/main/apis.yml
tags:
- Blockchain
- Compliance
- Cross-Chain
- Currency
- Money
- Payments
- Stablecoins
- Transfers
- USDC
- Wallets
tags_raw:
- Blockchain
- Compliance
- Cross-Chain
- Currency
- Money
- Payments
- Stablecoin
- Transfers
- USDC
- Wallets
type: Index
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: freemium
  onboarding: self-serve
  trial: false
  try_now: true
  public: false
  label: Freemium · Self-serve signup
  confidence: medium
  source:
  - plans
  - authentication
  - security
  generated: '2026-09-03'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/circle.png
access: 3rd-Party
created: '2024-11-07'
modified: '2026-05-30'
position: Consuming
specificationVersion: '0.23'
description: Circle Internet Financial is the issuer of USDC and EURC and operates a developer platform for moving regulated
  stablecoin money across the internet. Their APIs cover programmable wallets (developer- and user-controlled), gas sponsorship,
  the Cross-Chain Transfer Protocol (CCTP), Gateway unified balances, the Smart Contract Platform, the Circle Payments Network
  (CPN) for cross-border payments, compliance, StableFX trading on Arc, and xReserve for issuing USDC-backed stablecoins.
apis:
- aid: circle:gas-station
  name: Gas Station and Paymaster
  tags:
  - Gas Sponsorship
  - Paymaster
  - USDC
  humanURL: https://developers.circle.com/w3s/gas-station
  baseURL: https://api.circle.com/v1/w3s
  properties:
  - url: https://developers.circle.com/w3s/gas-station
    type: Documentation
  description: Sponsor gas fees on behalf of users or let users pay gas in USDC via Circle Paymaster, removing native-token
    friction from onboarding.
- aid: circle:circle-nfts-api
  name: Circle NFTs API
  description: The NFTs API from Circle — 1 operation(s) for nfts.
  humanURL: https://developers.circle.com/w3s/programmable-wallets
  baseURL: https://api.circle.com/v1/w3s
  tags:
  - NFT
  tags_raw:
  - NFTs
  properties:
  - type: OpenAPI
    url: openapi/circle-nfts-api-openapi.yml
  - type: Documentation
    url: https://developers.circle.com/w3s/programmable-wallets
  - type: Documentation
    url: https://developers.circle.com/w3s/user-controlled-wallets
  - type: Documentation
    url: https://developers.circle.com/cctp
  - type: Documentation
    url: https://developers.circle.com/gateway
  - type: Documentation
    url: https://developers.circle.com/w3s/smart-contract-platform
  - type: Documentation
    url: https://developers.circle.com/cpn
  - type: Documentation
    url: https://developers.circle.com/w3s/compliance-engine
  - type: Documentation
    url: https://developers.circle.com/stablefx
  - type: Documentation
    url: https://developers.circle.com/xreserve
- aid: circle:circle-signing-api
  name: Circle Signing API
  description: The Signing API from Circle — 4 operation(s) for signing.
  humanURL: https://developers.circle.com/w3s/programmable-wallets
  baseURL: https://api.circle.com/v1/w3s
  tags:
  - Signing
  properties:
  - type: OpenAPI
    url: openapi/circle-signing-api-openapi.yml
  - type: Documentation
    url: https://developers.circle.com/w3s/programmable-wallets
  - type: Documentation
    url: https://developers.circle.com/w3s/user-controlled-wallets
  - type: Documentation
    url: https://developers.circle.com/cctp
  - type: Documentation
    url: https://developers.circle.com/gateway
  - type: Documentation
    url: https://developers.circle.com/w3s/smart-contract-platform
  - type: Documentation
    url: https://developers.circle.com/cpn
  - type: Documentation
    url: https://developers.circle.com/w3s/compliance-engine
  - type: Documentation
    url: https://developers.circle.com/stablefx
  - type: Documentation
    url: https://developers.circle.com/xreserve
- aid: circle:circle-tokens-api
  name: Circle Tokens API
  description: The Tokens API from Circle — 1 operation(s) for tokens.
  humanURL: https://developers.circle.com/w3s/programmable-wallets
  baseURL: https://api.circle.com/v1/w3s
  tags:
  - Tokens
  properties:
  - type: OpenAPI
    url: openapi/circle-tokens-api-openapi.yml
  - type: Documentation
    url: https://developers.circle.com/w3s/programmable-wallets
  - type: Documentation
    url: https://developers.circle.com/w3s/user-controlled-wallets
  - type: Documentation
    url: https://developers.circle.com/cctp
  - type: Documentation
    url: https://developers.circle.com/gateway
  - type: Documentation
    url: https://developers.circle.com/w3s/smart-contract-platform
  - type: Documentation
    url: https://developers.circle.com/cpn
  - type: Documentation
    url: https://developers.circle.com/w3s/compliance-engine
  - type: Documentation
    url: https://developers.circle.com/stablefx
  - type: Documentation
    url: https://developers.circle.com/xreserve
- aid: circle:circle-transactions-api
  name: Circle Transactions API
  description: The Transactions API from Circle — 12 operation(s) for transactions.
  humanURL: https://developers.circle.com/w3s/programmable-wallets
  baseURL: https://api.circle.com/v1/w3s
  tags:
  - Transaction
  tags_raw:
  - Transactions
  properties:
  - type: OpenAPI
    url: openapi/circle-transactions-api-openapi.yml
  - type: Documentation
    url: https://developers.circle.com/w3s/programmable-wallets
  - type: Documentation
    url: https://developers.circle.com/w3s/user-controlled-wallets
  - type: Documentation
    url: https://developers.circle.com/cctp
  - type: Documentation
    url: https://developers.circle.com/gateway
  - type: Documentation
    url: https://developers.circle.com/w3s/smart-contract-platform
  - type: Documentation
    url: https://developers.circle.com/cpn
  - type: Documentation
    url: https://developers.circle.com/w3s/compliance-engine
  - type: Documentation
    url: https://developers.circle.com/stablefx
  - type: Documentation
    url: https://developers.circle.com/xreserve
- aid: circle:circle-wallet-sets-api
  name: Circle Wallet Sets API
  description: The Wallet Sets API from Circle — 4 operation(s) for wallet sets.
  humanURL: https://developers.circle.com/w3s/programmable-wallets
  baseURL: https://api.circle.com/v1/w3s
  tags:
  - Wallet Sets
  properties:
  - type: OpenAPI
    url: openapi/circle-wallet-sets-api-openapi.yml
  - type: Documentation
    url: https://developers.circle.com/w3s/programmable-wallets
  - type: Documentation
    url: https://developers.circle.com/w3s/user-controlled-wallets
  - type: Documentation
    url: https://developers.circle.com/cctp
  - type: Documentation
    url: https://developers.circle.com/gateway
  - type: Documentation
    url: https://developers.circle.com/w3s/smart-contract-platform
  - type: Documentation
    url: https://developers.circle.com/cpn
  - type: Documentation
    url: https://developers.circle.com/w3s/compliance-engine
  - type: Documentation
    url: https://developers.circle.com/stablefx
  - type: Documentation
    url: https://developers.circle.com/xreserve
- aid: circle:circle-wallets-api
  name: Circle Wallets API
  description: The Wallets API from Circle — 7 operation(s) for wallets.
  humanURL: https://developers.circle.com/w3s/programmable-wallets
  baseURL: https://api.circle.com/v1/w3s
  tags:
  - Wallets
  properties:
  - type: OpenAPI
    url: openapi/circle-wallets-api-openapi.yml
  - type: Documentation
    url: https://developers.circle.com/w3s/programmable-wallets
  - type: Documentation
    url: https://developers.circle.com/w3s/user-controlled-wallets
  - type: Documentation
    url: https://developers.circle.com/cctp
  - type: Documentation
    url: https://developers.circle.com/gateway
  - type: Documentation
    url: https://developers.circle.com/w3s/smart-contract-platform
  - type: Documentation
    url: https://developers.circle.com/cpn
  - type: Documentation
    url: https://developers.circle.com/w3s/compliance-engine
  - type: Documentation
    url: https://developers.circle.com/stablefx
  - type: Documentation
    url: https://developers.circle.com/xreserve
common:
- type: AgentSkills
  url: https://developers.circle.com/ai/skills
- type: APIReference
  url: https://developers.circle.com/api-reference
- type: MCPServer
  url: https://developers.circle.com/ai/mcp
- type: AgenticAccess
  url: agentic-access/circle-agentic-access.yml
- type: DomainSecurity
  url: security/circle-domain-security.yml
- type: Authentication
  url: authentication/circle-authentication.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/circleco
- type: Website
  url: https://www.circle.com/
- type: Portal
  url: https://developers.circle.com/
- type: Console
  url: https://console.circle.com/
- type: Authentication
  url: https://developers.circle.com/w3s/authentication
- type: GettingStarted
  url: https://developers.circle.com/w3s/getting-started
- type: StatusPage
  url: https://status.circle.com/
- type: Support
  url: https://support.usdc.circle.com/
- type: Blog
  url: https://www.circle.com/blog
- type: Community
  url: https://discord.com/invite/buildoncircle
- type: GitHubOrganization
  url: https://github.com/circlefin
- type: PrivacyPolicy
  url: https://www.circle.com/legal/privacy-policy
- type: TermsOfService
  url: https://www.circle.com/legal/terms-of-service
- type: JSONLD
  url: json-ld/circle-context.jsonld
- type: JSONSchema
  url: json-schema/circle-wallet-schema.json
- type: JSONSchema
  url: json-schema/circle-transaction-schema.json
- type: AsyncAPI
  url: asyncapi/circle-webhooks-asyncapi.yml
- type: Spectral
  url: rules/circle-rules.yml
- type: LlmsText
  url: https://developers.circle.com/llms.txt
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

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