API3

API3 is a first-party blockchain oracle network that connects real-world APIs directly to smart contracts without intermediary nodes. Its core technology is Airnode, a serverless oracle node that API providers operate themselves, cryptographically signing data before serving it on-chain. The API3 Market enables dApp developers to subscribe to managed decentralized APIs (dAPIs) — aggregated, multi-source data feeds covering 150+ price pairs across 40+ EVM chains — without speaking to a sales rep or signing a contract. API3's OEV (Oracle Extractable Value) mechanism captures MEV that traditionally leaks to bots around oracle updates and redistributes 80% of that revenue to the dApps reading the feeds, creating a net-positive oracle revenue model. The DAO governs the network via staked API3 tokens.

API3 publishes 6 API contracts indexed on the APIs.io network, including Airnodes API, Signed Data API, Status API, and 3 more. Tagged areas include Blockchain, Oracle, Decentralized, Data Feed, and Price Feeds.

The API3 catalog on APIs.io includes 1 JSON-LD context and 1 Spectral governance ruleset.

API3’s developer surface includes authentication, documentation, engineering blog, and 15 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

33.1/100 thin ▬ flat Agent 24/100 agent aware Front door AI 1/6 silent Heartbeat 50/100 alive saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessFreemiumSelf serve⚡ Free to try

1 published contract

Blockchain Oracle Decentralized Data Feed Price Feeds Web3 DeFi Smart ContractsOEVdAPI

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 33.1/100 · thin

Contract Quality 10.7 / 19

Developer Ergonomics 6.1 / 15

Access Clarity 1.2 / 15

Operational Transparency 1.0 / 10

Contract Governance 1.2 / 9

Discoverability 5.0 / 8

Regulatory Posture 2.5 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 24/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 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

Pagination 0 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) 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/.

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Agent readiness — checks not met, largest first (exact, from this profile):

MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document
Delegated User Identity +6 pts — a served discovery document listing authorization_code in grant_types_supported (served), else an oauth2 authorizationCode flow or openIdConnect declared in an OpenAPI (documented)

9 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Access Clarity scores 7.9 — up to +18.4 composite points
Developer Ergonomics scores 40.5 — up to +11.9 composite points
Operational Transparency scores 10.5 — up to +11.6 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

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 the provider profile at artifacts.apis.io/api3/apis.yml: open an issue on github.com/api-evangelist/api3 to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

OpenAPI

measured — observed by APIs.io (published)

APIs 6

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

API3 dAPI Data Feeds

Managed decentralized API (dAPI) data feeds sourced directly from first-party oracle nodes operated by the data providers themselves. Each feed aggregates signed data from multi...

API3 OEV Rewards

Oracle Extractable Value (OEV) Rewards is API3's revenue-sharing mechanism for dApps that integrate OEV-enabled Api3ReaderProxyV1 proxy contracts. When liquidation or arbitrage ...

API3 Airnode HTTP Gateway

The Airnode HTTP gateway exposes a REST endpoint that allows authorized callers to query an Airnode operator's API data off-chain without sending a blockchain transaction. API p...

API3 Airnodes API

Airnode address discovery

API3 Signed Data API

Reading and writing cryptographically signed oracle data

API3 Status API

Health and deployment information

Open Collections 3

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

API3 Signed Airnodes API

OPEN COLLECTION

API3 Signed Airnodes Signed Data API

OPEN COLLECTION

API3 Signed Airnodes Status API

OPEN COLLECTION

API3 pricing

Not yet checked against API3's own pricing page. Compiled by API Evangelist on 2026-06-13 from docs.api3.org/dapps/integration/; confirm before you rely on a figure. A free plan or tier is listed.

Plan	Price
Testnet Trial Plan trial	Free
Mainnet Standard Plan usage-based	—
OEV Rewards (Revenue Share) revenue-share	—

Plan details, limits and sources →

Rate limits

On-chain dAPI read (IProxy.read): unlimited calls per block
API3 Market web API: unlimited requests per minute
Airnode HTTP Gateway: unlimited requests per second

Compiled by API Evangelist, not yet checked against API3's documentation. Rate-limit details →

Pricing Plans 1

Published pricing tiers and plan structures.

Api3 Plans

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Api3 Rate Limits

3 limits

RATE LIMITS

Service Levels 1

Uptime the provider promises or reports, as SLA4OAI. Read from its own pages; APIs.io runs no monitors.

API3

SLA

FinOps 1

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

Api3 Finops

FINOPS

Semantic Vocabularies 1

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

Api3 Context

6 classes · 8 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

API3 API Rules

52 rules · 50 errors 1 warnings 1 info

SPECTRAL

Security Posture 2

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

Api3 Authentication

http · 1 scheme

SECURITY

Api3 Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

Agentic Access 1

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

Api3 Agentic Access

4 operations · 1 acting

AGENTIC

Resources

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

OpenAPI

OpenAPI

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Design & Contract 1

Pagination, idempotency, versioning, errors, and events

JSONLD

JSONLD

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 3

Status, limits, changes, and where to get help

Discord

Discord

Forums

Forums

RateLimits

RateLimits

Commercial 2

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

Company 3

The organization behind the API

Website

Website

Blog

Blog

Twitter

Twitter

Other 3

Properties that don't map to a standard resource type

Telegram

Staking

Staking

Market

Market

Source (apis.yml)

aid: api3
url: https://raw.githubusercontent.com/api-evangelist/api3/refs/heads/main/apis.yml
name: API3
kind: company
description: API3 is a first-party blockchain oracle network that connects real-world APIs directly to smart contracts without
  intermediary nodes. Its core technology is Airnode, a serverless oracle node that API providers operate themselves, cryptographically
  signing data before serving it on-chain. The API3 Market enables dApp developers to subscribe to managed decentralized APIs
  (dAPIs) — aggregated, multi-source data feeds covering 150+ price pairs across 40+ EVM chains — without speaking to a sales
  rep or signing a contract. API3's OEV (Oracle Extractable Value) mechanism captures MEV that traditionally leaks to bots
  around oracle updates and redistributes 80% of that revenue to the dApps reading the feeds, creating a net-positive oracle
  revenue model. The DAO governs the network via staked API3 tokens.
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
  gated: none
  gated_source:
  - onboarding
  label: Freemium · Self-serve signup
  confidence: medium
  source:
  - plans
  - authentication
  - security
  generated: '2026-11-06'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/api3.png
x-docs-platform: vitepress
x-docs-platform-confidence: medium
x-docs-platform-checked: 2026-09-19
x-docs-hosting: firebase
tags:
- Blockchain
- Oracle
- Decentralized
- Data Feed
- Price Feeds
- Web3
- DeFi
- Smart Contracts
- OEV
- dAPI
tags_raw:
- Blockchain
- Oracle
- Decentralized
- Data Feeds
- Price Feeds
- Web3
- DeFi
- Smart Contracts
- OEV
- dAPI
type: Index
access: 3rd-Party
position: Consuming
created: '2026-06-13'
modified: '2026-06-13'
specificationVersion: '0.23'
apis:
- aid: api3:dapi-data-feeds
  name: API3 dAPI Data Feeds
  description: Managed decentralized API (dAPI) data feeds sourced directly from first-party oracle nodes operated by the
    data providers themselves. Each feed aggregates signed data from multiple Airnode operators and is updated on-chain based
    on deviation thresholds (0.25%, 0.5%, 1%, 2.5%, or 5%) and a 24-hour heartbeat. Smart contracts read feeds via the IProxy/AggregatorV2V3Interface-compatible
    Api3ReaderProxyV1 contract. Over 150 asset pairs — crypto, forex, equities, and commodities — are available across 40+
    EVM networks. Subscriptions are purchased through the API3 Market; testnet plans are 7-day trials and mainnet plans are
    3-month subscriptions.
  humanURL: https://market.api3.org/
  baseURL: https://market.api3.org
  tags:
  - Data Feed
  - Price Feeds
  - dAPI
  - Oracle
  - DeFi
  - EVM
  tags_raw:
  - Data Feeds
  - Price Feeds
  - dAPI
  - Oracle
  - DeFi
  - EVM
  properties:
  - type: Documentation
    url: https://docs.api3.org/dapps/
  - type: Integrations
    url: https://docs.api3.org/dapps/integration/
  - type: GettingStarted
    url: https://docs.api3.org/dapps/
  x-features:
  - 150+ price pairs (crypto, forex, equities, commodities)
  - Configurable deviation thresholds (0.25% – 5%)
  - 24-hour heartbeat interval
  - AggregatorV2V3Interface-compatible proxy contracts
  - 40+ EVM chains including Ethereum, Arbitrum, Base, BNB Chain, Polygon, Avalanche
  - No minimum commitment; pay-as-you-go subscription
  x-use-cases:
  - DeFi lending protocols needing reliable collateral price feeds
  - Derivatives and perpetuals platforms requiring low-latency mark prices
  - Stablecoin systems referencing external price anchors
  - Prediction markets and options protocols reading settlement prices
- aid: api3:oev-rewards
  name: API3 OEV Rewards
  description: Oracle Extractable Value (OEV) Rewards is API3's revenue-sharing mechanism for dApps that integrate OEV-enabled
    Api3ReaderProxyV1 proxy contracts. When liquidation or arbitrage opportunities arise around oracle updates, API3 runs
    an auction on the OEV Network and captures the resulting MEV. 80% of auction proceeds are paid monthly in the native gas
    token of the dApp's deployed chain to the wallet the dApp designates. Integration requires deploying a custom proxy (free
    via the API3 Market) rather than the generic shared proxy, and registering a recipient wallet address with an API3 representative.
  humanURL: https://docs.api3.org/dapps/oev-rewards/
  baseURL: https://market.api3.org
  tags:
  - OEV
  - MEV
  - Revenue Sharing
  - DeFi
  - Oracle
  properties:
  - type: Documentation
    url: https://docs.api3.org/dapps/oev-rewards/
  - type: GettingStarted
    url: https://docs.api3.org/dapps/oev-rewards/
  x-features:
  - 80% of OEV auction proceeds returned to dApp
  - Monthly payouts in native chain gas token
  - No code changes to smart contracts required
  - Custom proxy deployment via API3 Market
  - Supported on all 40+ API3 chain deployments
  x-use-cases:
  - Lending protocols (Compound, Morpho, Moonwell) offsetting oracle costs
  - Any DeFi application using API3 dAPI feeds to generate passive revenue
  - Treasury diversification via oracle MEV redistribution
- aid: api3:airnode-http-gateway
  name: API3 Airnode HTTP Gateway
  description: The Airnode HTTP gateway exposes a REST endpoint that allows authorized callers to query an Airnode operator's
    API data off-chain without sending a blockchain transaction. API providers configure the gateway in their Airnode's nodeSettings,
    protecting it with an API key. Responses contain the same cryptographically signed data that is eventually posted on-chain,
    enabling off-chain verification, testing, and direct signed-data consumption by third-party data push relayers. The OEV
    Gateway variant is used by auction searchers to retrieve Airnode-signed price updates that can only be used by the winning
    OEV auction bidder.
  humanURL: https://old-docs.api3.org/airnode/pre-alpha/
  baseURL: https://airnode.api3.org
  tags:
  - Airnode
  - HTTP Gateway
  - Signed Data
  - OEV
  - REST
  properties:
  - type: Documentation
    url: https://old-docs.api3.org/airnode/pre-alpha/
  x-features:
  - API-key-protected REST endpoint per Airnode deployment
  - Returns cryptographically signed data from the source API provider
  - Enables off-chain data consumption without on-chain transactions
  - OEV Gateway variant restricts signed data to winning auction bidder
  x-use-cases:
  - Off-chain testing of Airnode data before on-chain integration
  - Third-party push relayers submitting signed data to chain
  - OEV searchers fetching price updates to submit winning auction bids
- aid: api3:api3-airnodes-api
  name: API3 Airnodes API
  description: Airnode address discovery
  humanURL: https://market.api3.org/
  baseURL: https://market.api3.org
  tags:
  - Airnodes
  properties:
  - type: OpenAPI
    url: openapi/api3-airnodes-api-openapi.yml
- aid: api3:api3-signed-data-api
  name: API3 Signed Data API
  description: Reading and writing cryptographically signed oracle data
  humanURL: https://market.api3.org/
  baseURL: https://market.api3.org
  tags:
  - Signed Data
  properties:
  - type: OpenAPI
    url: openapi/api3-signed-data-api-openapi.yml
- aid: api3:api3-status-api
  name: API3 Status API
  description: Health and deployment information
  humanURL: https://market.api3.org/
  baseURL: https://market.api3.org
  tags:
  - Status
  properties:
  - type: OpenAPI
    url: openapi/api3-status-api-openapi.yml
common:
- type: AgenticAccess
  url: agentic-access/api3-agentic-access.yml
- type: DomainSecurity
  url: security/api3-domain-security.yml
- type: Authentication
  url: authentication/api3-authentication.yml
- type: Website
  url: https://api3.org/
- type: Documentation
  url: https://docs.api3.org/
- type: Blog
  url: https://blog.api3.org/
- type: GitHubOrganization
  url: https://github.com/api3dao
- type: Discord
  url: https://discord.gg/qnRrcfnm5W
- type: Twitter
  url: https://twitter.com/API3DAO
- type: Telegram
  url: https://t.me/API3DAO
- type: Forums
  url: https://forum.api3.org/
- type: Staking
  url: https://stake.api3.org/
- type: Market
  url: https://market.api3.org/
- type: OpenAPI
  url: openapi/_original/api3-signed-api-openapi.yml
- type: JSONLD
  url: json-ld/api3-context.jsonld
- type: Plans
  url: plans/api3-plans.yml
- type: RateLimits
  url: rate-limits/api3-rate-limits.yml
- type: FinOps
  url: finops/api3-finops.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

API3 — frequently asked questions

Does API3 have an API?

Yes. APIs.io lists 6 APIs from API3, including API3 dAPI Data Feeds, API3 OEV Rewards and API3 Airnode HTTP Gateway, and 3 more.

Is there an OpenAPI specification for the API3?

Yes. APIs.io indexes 3 OpenAPI specifications for API3, each linked for download from this page.

How do I authenticate with the API3?

API3 uses bearer-token authentication (http · 1 scheme). The details are profiled on APIs.io as Api3 Authentication.

How much does the API3 cost?

APIs.io lists 3 pricing plans for API3, with each plan's price, limits and inclusions under Pricing on this page.

Is the API3 ready for AI agents?

API3 has a Kin Score of 33.1 out of 100 (thin) and an Agent Readiness score of 23.7 (agent-aware), scored by API Evangelist on 2026-11-06.

Work with this as data

Every provider here is available over the APIs.io API and to AI agents over MCP.

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get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
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