API3

• Name: API3
• URL: https://api3.org/
• Category: oracle protocol / first-party oracle network / data-feed market
• Tags: ethereum-ecosystem
• Summary: API3 is a first-party oracle stack. Providers run Airnode, sign their own data, and API3 sells the route into dApp-facing proxies. That is the useful cut: source certification, feed activation, proxy routing, and optional OEV capture—not just another oracle network.
• What it does:
  • Enables API providers to operate their own oracle nodes through Airnode instead of depending on third-party node operators
  • Publishes data feeds to EVM chains through Api3ReaderProxyV1 contracts and sells activation plans through Api3 Market
  • Lets dApps choose update policies such as deviation thresholds and heartbeat-backed operating periods
  • Offers dApp-specific proxy addresses that can be OEV-enabled for revenue sharing
  • Exposes public verification paths for first-party-source claims through signed APIs, certified Airnode addresses, and deterministic proxy-address computation tools
  • Packages contracts, chain metadata, deployment addresses, dApp registries, and proxy-address computation utilities in the official contracts repository
• Key claims:
  • The API3 whitepaper defines dAPIs as services composed of first-party oracles operated by the API providers themselves rather than by third-party middlemen, and frames that as the core difference from older source-agnostic oracle models.
  • Current docs operationalize that claim with a concrete audit surface: a first-party source must operate an independent API business, certify its Airnode public key, and publish signed data itself. The docs even show how users can inspect a provider-hosted signed API and verify the certified Airnode address used for a feed.
  • Api3 Market turns oracle consumption into a purchasable plan surface. Users buy plans with explicit deviation thresholds and a heartbeat interval, and the docs say pricing is based on estimated operating cost rather than markup because monetization is designed around OEV.
  • The official contracts package exposes another important control plane: chain metadata, dApp registries, deterministic communal and dApp-specific proxy-address computation, deployment-address metadata, and contracts that facilitate both data feeds and OEV auctions.
  • Airnode is the critical implementation detail that makes the first-party-oracle claim plausible. The Airnode node repository describes it as the node component that connects multiple blockchains to the outside world and shows dedicated modules for authorization, request handling, templates, verification, fulfillments, and heartbeat/reporting.
  • Compared with other oracle systems, API3 is not mainly asking who can report a price; it is asking who is allowed to be a source, how that source certifies itself, how feeds get activated and paid for, and how dApp-specific proxy routing changes downstream economics.
  • The main remaining choke points still sit with Api3-managed market and curation surfaces: the offered update-policy menu is narrow, dApp registration appears in official metadata and tooling, and OEV-enabled integrations rely on Api3-managed aliasing and proxy-routing conventions.
• Whitepaper: The strongest primary materials in this pass were the official API3 whitepaper PDF, the live docs export, the contracts repository, and the Airnode node repository; see ../whitepapers/api3-primary-sources-2026-05-11.md.
• Sources:
  • https://api3.org/
  • https://docs.api3.org/llms-full.txt
  • https://github.com/api3dao/api3-whitepaper
  • https://raw.githubusercontent.com/api3dao/api3-whitepaper/master/api3-whitepaper.tex
  • https://github.com/api3dao/contracts
  • https://raw.githubusercontent.com/api3dao/contracts/main/README.md
  • https://github.com/api3dao/airnode
  • https://raw.githubusercontent.com/api3dao/airnode/master/packages/airnode-node/README.md

Internal linkages

• Core lower-layer implementation note: airnode.
• Strongest peer comparison: chainlink.
• Distinct same-stack extension: api3-oev.

Control surface

• The contracts are the easy part to inspect: reader proxies, beacon / dAPI read paths, and OEV-enabled proxy addresses.

• The harder control sits in source certification, feed-plan curation, dApp registration, proxy mapping, and the Airnode + signed-API operating path behind those contracts.

• Read API3 as a source-certification and feed-routing business wrapped around oracle contracts. That is also where the governance risk lives.

• Last reviewed: 2026-05-30 UTC