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Hunter

Hunter.io is an email-intelligence and outbound platform that finds, verifies, and enriches professional email addresses at scale. Its public APIs cover Domain Search, Email Finder, Email Verifier, Email Count, Discover (company prospecting), Person/Company/Combined Enrichment, Leads management, and Account/usage inspection. Credit-based metering, plan-tiered monthly allowances, and per-endpoint rate limits make it a reference example of a usage-based B2B data API.

agent ready

Reference-quality API operations across every facet — a rich contract, published governance, transparent operations, and machine-readable commercial terms.

Kin Score

API Evangelist profiles Hunter the way a machine reads it — 69 machine-readable artifacts across 8 APIs, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.

Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Hunter scores 70.3/100 (exemplar), with a separate agent-readiness read of 56/100 (agent ready). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.

Kin Score

This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.

Kin Score Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5
Composite quality — 70.3/100 · exemplar
Contract Quality 18.8 / 25
Developer Ergonomics 11.3 / 20
Commercial Clarity 12.1 / 20
Operational Transparency 8.9 / 13
Governance 10.4 / 12
Discoverability 8.8 / 10
Agent readiness — 56/100 · agent ready
Machine-Readable Contract 18 / 18
Agentic Access Contract 15 / 15
MCP Server 0 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 8 / 8
Request/Response Examples 0 / 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

How we profile Hunter

Each block below is one kind of artifact we hold for Hunter. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.

APIs 8

Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.

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

Hunter Account API

Account metadata and usage counters.

Hunter Discover API

Company discovery and prospecting.

Hunter Domain Search API

Discover all emails for a domain or company.

Hunter Email Count API

Count emails for a domain.

Hunter Email Finder API

Find the email address of a person at a company.

Hunter Email Verifier API

Verify the deliverability of an email address.

Hunter Enrichment API

Person, company, and combined enrichment.

Hunter Leads API

Lead management.

Scroll within the panel for all 8 ·

Postman Collections 8

A runnable collection turns the contract into something a developer can execute in seconds. We profile them because the fastest way to trust an API is to make a real call against it.

Ready-to-run Postman collections for exercising this provider's APIs.

Scroll within the panel for all 8 ·

Open Collections 8

Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.

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

Hunter Account API

OPEN COLLECTION

Hunter Discover API

OPEN COLLECTION

Hunter Domain Search API

OPEN COLLECTION

Hunter Email Count API

OPEN COLLECTION

Hunter Email Finder API

OPEN COLLECTION

Hunter Email Verifier API

OPEN COLLECTION

Hunter Enrichment API

OPEN COLLECTION

Hunter Leads API

OPEN COLLECTION

Scroll within the panel for all 8 ·

Arazzo Workflows 11

Real integrations are rarely a single call. Arazzo describes the multi-step sequences — auth, then create, then confirm — so both a human and an agent can follow the choreography, not just the endpoints.

Multi-step API workflows described with the Arazzo specification.

Hunter Add Verified Lead To List

Verify an email, upsert it as a lead, then assign the lead to a target leads list.

ARAZZO

Hunter Author Finder

Resolve an author's email from their name and publication domain, verify it, then enrich their profile.

ARAZZO

Hunter Campaign Lead Builder

Find a contact, verify it, and seed a campaign by creating a verified lead in a target list.

ARAZZO

Hunter Count Gated Domain Search

Use the free Email Count to confirm coverage before spending a credit on Domain Search.

ARAZZO

Hunter Credit Guarded Domain Search

Check account search credits first and run a Domain Search only when credits remain.

ARAZZO

Hunter Discover To Domain Emails

Discover companies matching a target profile, then pull the email list for the top match's domain.

ARAZZO

Hunter Domain To Verified Email

Discover a domain's email pattern, find a specific person's email, then verify its deliverability.

ARAZZO

Hunter Enrich Email To Lead

Combined-enrich an email into person and company data, then upsert a fully populated lead.

ARAZZO

Hunter Find Verify Create Lead

Find a person's email, verify it, and create a lead only when the address is deliverable.

ARAZZO

Hunter Reverify Lead

Retrieve a stored lead, re-verify its email, and update or delete it based on the result.

ARAZZO

Hunter Verify Existing Email

Verify a known email and upsert it into Hunter as a lead with its verification status.

ARAZZO

Scroll within the panel for all 11 ·

GraphQL 1

Where a provider ships GraphQL, the schema is the contract. We profile it alongside the REST surface so the whole interface is legible in one place.

GraphQL schemas published by this provider.

Hunter.io GraphQL Schema

Conceptual GraphQL schema for the Hunter.io email intelligence and outbound platform, derived from the Hunter.io REST API (https://hunter.io/api-documentation/v2).

GRAPHQL

Pricing Plans 1

Pricing is part of the interface. Machine-readable plans tell you what a tier costs and includes before you commit — one of the six things the Kin Score reads for commercial clarity.

Published pricing tiers and plan structures.

Rate Limits 1

Rate limits are the difference between a demo that works and a production integration that doesn't fall over. Publishing them is an operational-transparency signal — and a hard requirement for any agent that plans its own throughput.

Documented rate limits and quota policies.

Hunter Io Rate Limits

8 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals let a buyer model the financial operations of an API before it's live. We profile them for the same reason we profile pricing: the money is part of the contract.

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

Features 17

The notable capabilities this provider advertises, captured as structured features so they can be searched and compared instead of read one landing page at a time.

Notable capabilities this provider offers.

Domain Search returns all emails for a domain with sources, confidence, department, and seniority
Email Finder predicts the most likely address for a person at a company with 0-100 confidence
Email Verifier runs MX, SMTP, regex, disposable, webmail, accept-all, and block checks plus database lookup
Email Count is free and unauthenticated for pre-flight sizing of a domain's email footprint
Discover API for company prospecting via natural language or structured filters
Person, company, and combined enrichment with optional Clearbit-shape response for drop-in migration
Leads API with CRUD, upsert, filtered list, custom attributes, and lead-list scoping
Campaigns API for outbound sequences, recipients, opens, clicks, replies, and unsubscribes
Account API returns plan, reset date, and per-meter usage counters for FinOps
{"Three auth modes"=>"api_key query, X-API-KEY header, or Authorization Bearer"}
Token-bucket-style per-endpoint rate limits with 429 responses (5-15 rps, 50-500 rpm)
Monthly credit allowances per plan with reset_date semantics
Chrome and Firefox browser extensions, Google Sheets add-on, and Bulk Tasks UI
Native integrations with Salesforce, HubSpot, Zapier, Pipedrive, Zoho CRM, and many outbound tools
Hunter MCP server and ChatGPT MCP server for agentic email-finder workflows
Hunter Claude Plugin for find, verify, and enrich workflows inside Claude
GDPR-aligned data handling with 451 responses on restricted personal data

Scroll within the panel for all 17 ·

Semantic Vocabularies 1

JSON-LD contexts give the data shared meaning across APIs. We profile them because semantics are what let a machine reconcile 'customer' here with 'customer' somewhere else.

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

Hunter Io Context

0 classes · 4 properties

JSON-LD

Spectral Rules 2

Governance rulesets we run against this provider's specs — the automated checks behind parts of the score. Profiling them makes the quality bar explicit and re-runnable, not a matter of opinion.

Hunter API Rules

5 rules · 4 warnings

SPECTRAL

Hunter API Rules

10 rules · 5 errors · 4 warnings

SPECTRAL

JSON Schema 3

Standalone JSON Schema definitions describe the data models behind the API. We profile them so the shapes are validatable on their own — useful long after a single request is forgotten.

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

Hunter Email

13 properties

JSON SCHEMA

Hunter Lead

24 properties

JSON SCHEMA

Hunter Email Verification Result

14 properties

JSON SCHEMA

JSON Structure 1

JSON Structure captures the data shapes in a form built for tooling — a complement to JSON Schema that keeps the model machine-legible.

JSON Structure definitions describing this provider's data shapes.

Hunter Io Structure

0 properties

JSON STRUCTURE

Examples 3

Real request and response payloads are what turn a spec from abstract into obvious — and they're one of the twelve things an agent needs to call an API correctly on the first try.

Example request and response payloads for these APIs.

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.

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

Hunter Io Authentication

apiKey/http · 3 schemes

SECURITY

Hunter Io Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

Agentic Access 1

An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.

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

Hunter Io Agentic Access

15 operations · 5 acting

15 operations · 5 acting

AGENTIC

Resources

Every other property we hold for Hunter — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.

Get Started 3

Portal, sign-up, and the first successful call

Documentation 2

Reference material describing how the API behaves

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

Access & Security 3

Authentication, authorization, and security posture

Company 1

The organization behind the API

Other 2

Properties that don't map to a standard resource type

← All providers · Data indexed from github.com/api-evangelist/hunter-io · machine-readable index on apis.io