1Lookup

1Lookup is a self-serve data verification and enrichment platform for SMBs, exposing more than forty products through a single REST API and one universal credit balance. It validates phone numbers (line type, carrier, HLR reachability, number portability, DNC status, spam/scam reputation, fraud score), email addresses (syntax, MX, deliverability, disposable and role-based detection) and IP addresses (geolocation, VPN/proxy/Tor and datacenter detection), then extends into B2B company and contact data (firmographics, prospect and account search, contact append, skip trace), SEO and web intelligence (domain authority, backlinks, keyword metrics, audience reports, SERP and website scraping), social and media lookups, property data and audio transcription. The same engine powers a web dashboard with batch CSV validation, roughly twenty-five free rate-limited browser tools, and a first-party hosted MCP connector authorized with OAuth 2.1 that gives AI agents five of the core tools without an API key.

1Lookup publishes 3 APIs on the APIs.io network. Tagged areas include phone validation, email validation, IP intelligence, fraud & risk, and data enrichment.

The 1Lookup catalog on APIs.io includes 1 event-driven AsyncAPI specification.

1Lookup’s developer surface includes documentation, API reference, getting-started guide, engineering blog, support, pricing, signup flow, and 34 more developer resources.

🌐 Visit website 📡 Source on GitHub
62.4/100 strong ▲ 15.3 Agent 55/100 agent native Full breakdown ↓
scored 2026-08-17 · rubric v0.11.0
3 APIs 2 MCP Servers
phone validationemail validationIP intelligencefraud & riskdata enrichmentB2B contact & company dataSEO / web analyticsaudio transcriptionMCP / agent-nativeREST API

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-08-17 · rubric v0.11.0
Composite quality — 62.4/100 · strong
Contract Quality 12.9 / 25
Developer Ergonomics 13.8 / 20
Commercial Clarity 18.4 / 20
Operational Transparency 6.5 / 13
Governance 1.5 / 12
Discoverability 9.3 / 10
Agent readiness — 55/100 · agent native
Machine-Readable Contract 18 / 18
Agentic Access Contract 0 / 10
MCP Server 12 / 12
Machine-Readable Auth 10 / 10
Idempotency 9 / 9
Stable Error Semantics 8 / 8
Request/Response Examples 7 / 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
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/1lookup: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 3

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

1Lookup REST API

RESTful API over HTTPS covering all 1Lookup products (phone/email/IP validation, fraud, enrichment, B2B data, SEO intelligence). API-key Bearer auth (sk_live_ keys, organization...

1Lookup MCP Server

First-party hosted/remote MCP connector with OAuth 2.1 auth (authorization code + PKCE, dynamic client registration, single `lookup` scope) exposing 5 tools (validate_phone, ver...

1Lookup LLMs Index

Machine-readable content indexes (llms.txt and llms-full.txt) for AI and answer engines, indexing the free tools, every product page, the comparison pages and the key site secti...

MCP Servers 2

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

mcp

MCP SERVER

1lookup-mcp.yml

MCP SERVER

Pricing Plans 1

Published pricing tiers and plan structures.

1Lookup Plans Pricing

5 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

1Lookup Rate Limits

6 limits

RATE LIMITS

Event Specifications 1

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

1Lookup Webhooks

ASYNCAPI

Security Posture 4

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

1Lookup Authentication

http/oauth2 · 2 schemes

SECURITY

1Lookup Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

1Lookup Vulnerability Disclosure

Hackerone · contact published

SECURITY

1Lookup Trust Center

trust center published

SECURITY

Scopes 1

OAuth scopes governing access to this provider's APIs.

1Lookup Scopes

1 scope · authorizationCode

1 scopes

SCOPES

Resources

Get Started 5

Portal, sign-up, and the first successful call

DeveloperPortal
DeveloperPortal
 GettingStarted
GettingStarted
 SignUp
SignUp
 Login
Login
 Sandbox
Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation
Documentation
 APIReference
APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

WellKnown
WellKnown
 MCPServer
MCPServer
 LLMsTxt
LLMsTxt
 AgentSkill
AgentSkill

Design & Contract 7

Pagination, idempotency, versioning, errors, and events

Conventions
Conventions
 ErrorCatalog
ErrorCatalog
 Lifecycle
Lifecycle
 Conformance
Conformance
 Idempotency
Idempotency
 Webhooks
Webhooks
 DataModel
DataModel

Scroll for all 7

Build 3

SDKs, sample code, and the tooling you integrate with

Packages
Packages
 ToolCrosswalk
ToolCrosswalk
 Examples
Examples

Access & Security 7

Authentication, authorization, and security posture

Authentication
Authentication
 OAuthScopes
OAuthScopes
 Compliance
Compliance
 TrustCenter
TrustCenter
 Security
Security
 VulnerabilityDisclosure
VulnerabilityDisclosure
 DomainSecurity
DomainSecurity

Scroll for all 7

Learn 1

Tutorials, courses, talks, and written guidance

YouTube
YouTube

Operate 3

Status, limits, changes, and where to get help

Support
Support
 FAQ
FAQ
 RateLimits
RateLimits

Commercial 4

Pricing, plans, and the legal terms of use

Pricing
Pricing
 TermsOfService
TermsOfService
 PrivacyPolicy
PrivacyPolicy
 Plans
Plans

Company 4

The organization behind the API

Website
Website
 Blog
Blog
 LinkedIn
LinkedIn
 Twitter
Twitter

Other 1

Properties that don't map to a standard resource type

Glossary
Glossary

Source (apis.yml)

apis.yml Raw ↑ 
name: 1Lookup
description: 1Lookup is a self-serve data verification and enrichment platform for SMBs, exposing more than forty products
  through a single REST API and one universal credit balance. It validates phone numbers (line type, carrier, HLR reachability,
  number portability, DNC status, spam/scam reputation, fraud score), email addresses (syntax, MX, deliverability, disposable
  and role-based detection) and IP addresses (geolocation, VPN/proxy/Tor and datacenter detection), then extends into B2B
  company and contact data (firmographics, prospect and account search, contact append, skip trace), SEO and web intelligence
  (domain authority, backlinks, keyword metrics, audience reports, SERP and website scraping), social and media lookups, property
  data and audio transcription. The same engine powers a web dashboard with batch CSV validation, roughly twenty-five free
  rate-limited browser tools, and a first-party hosted MCP connector authorized with OAuth 2.1 that gives AI agents five of
  the core tools without an API key.
image: https://www.1lookup.io/images/featured/pages/homepage.png
url: https://1lookup.apievangelist.com/apis.yml
created: '2026-08-08'
modified: '2026-08-14'
specificationVersion: '0.21'
tags:
- phone validation
- email validation
- IP intelligence
- fraud & risk
- data enrichment
- B2B contact & company data
- SEO / web analytics
- audio transcription
- MCP / agent-native
- REST API
apis:
- name: 1Lookup REST API
  description: RESTful API over HTTPS covering all 1Lookup products (phone/email/IP validation, fraud, enrichment, B2B data,
    SEO intelligence). API-key Bearer auth (sk_live_ keys, organization-scoped), JSON bodies, one response envelope on every
    product, and job-based bulk processing up to 100,000 rows with an Idempotency-Key contract and signed webhook callbacks.
    46 documented operations, almost all POST, priced against a universal credit balance. No OpenAPI or other machine-readable
    contract is published.
  humanURL: https://app.1lookup.io/api
  baseURL: https://app.1lookup.io/api/v1
  tags:
  - phone validation
  - email validation
  - IP intelligence
  - fraud & risk
  - data enrichment
  - B2B contact & company data
  - SEO / web analytics
  - audio transcription
  - REST API
  properties:
  - type: Documentation
    url: https://app.1lookup.io/api
  - type: APIReference
    url: https://app.1lookup.io/api#endpoints
  - type: GettingStarted
    url: https://app.1lookup.io/api#getting-started
  - type: Authentication
    url: authentication/1lookup-authentication.yml
  - type: Conventions
    url: conventions/1lookup-conventions.yml
  - type: ErrorCatalog
    url: errors/1lookup-problem-types.yml
  - type: RateLimits
    url: rate-limits/1lookup-rate-limits.yml
  - type: Lifecycle
    url: lifecycle/1lookup-lifecycle.yml
  - type: Idempotency
    url: conventions/1lookup-conventions.yml
  - type: Webhooks
    url: asyncapi/1lookup-webhooks.yml
  - type: DataModel
    url: data-model/1lookup-data-model.yml
  - type: Examples
    url: examples/1lookup-examples.yml
- name: 1Lookup MCP Server
  description: First-party hosted/remote MCP connector with OAuth 2.1 auth (authorization code + PKCE, dynamic client registration,
    single `lookup` scope) exposing 5 tools (validate_phone, verify_email, ip_lookup, bulk_verify, get_account) for Claude,
    Cursor, ChatGPT, and any MCP client. Tool calls bill against the same plan credits as the REST API.
  humanURL: https://www.1lookup.io/products/mcp
  baseURL: https://app.1lookup.io/api/mcp
  tags:
  - MCP / agent-native
  - phone validation
  - email validation
  - IP intelligence
  properties:
  - type: MCPServer
    url: https://app.1lookup.io/api/mcp
  - type: MCPServer
    url: mcp/1lookup-mcp.yml
  - type: ToolCrosswalk
    url: mcp/1lookup-tool-crosswalk.yml
  - type: Documentation
    url: https://www.1lookup.io/products/mcp
  - type: OAuthScopes
    url: scopes/1lookup-scopes.yml
  - type: WellKnown
    url: https://www.1lookup.io/.well-known/mcp/server-card.json
- name: 1Lookup LLMs Index
  description: Machine-readable content indexes (llms.txt and llms-full.txt) for AI and answer engines, indexing the free
    tools, every product page, the comparison pages and the key site sections.
  humanURL: https://www.1lookup.io
  baseURL: https://www.1lookup.io
  tags:
  - MCP / agent-native
  properties:
  - type: LLMsTxt
    url: https://www.1lookup.io/llms.txt
  - type: LLMsTxt
    url: https://www.1lookup.io/llms-full.txt
  - type: LLMsTxt
    url: llms/1lookup-llms.txt
maintainers:
- FN: 1Lookup
  url: https://www.1lookup.io
  email: support@1lookup.io
generated:
  by: apis.io/add
  model: claude-opus-4-8
  confidence: 93
  at: '2026-08-08T11:53:32.811Z'
common:
- type: DeveloperPortal
  url: https://app.1lookup.io/api
- type: Documentation
  url: https://app.1lookup.io/api
- type: APIReference
  url: https://app.1lookup.io/api#endpoints
- type: GettingStarted
  url: https://app.1lookup.io/api#getting-started
- type: Website
  url: https://www.1lookup.io
- type: Blog
  url: https://www.1lookup.io/blog
- type: Support
  url: https://www.1lookup.io/contact
- type: Pricing
  url: https://www.1lookup.io/pricing
- type: SignUp
  url: https://app.1lookup.io/signup
- type: Login
  url: https://app.1lookup.io/login
- type: TermsOfService
  url: https://www.1lookup.io/terms
- type: PrivacyPolicy
  url: https://www.1lookup.io/privacy
- type: FAQ
  url: https://www.1lookup.io/faq
- type: Integrations
  url: https://www.1lookup.io/integrations
- type: Glossary
  url: https://www.1lookup.io/glossary
- type: LinkedIn
  url: https://linkedin.com/company/1lookup
- type: Twitter
  url: https://x.com/1LookupApp
- type: YouTube
  url: https://www.youtube.com/@1LookupApp
- type: Authentication
  url: authentication/1lookup-authentication.yml
- type: OAuthScopes
  url: scopes/1lookup-scopes.yml
- type: Conventions
  url: conventions/1lookup-conventions.yml
- type: ErrorCatalog
  url: errors/1lookup-problem-types.yml
- type: RateLimits
  url: rate-limits/1lookup-rate-limits.yml
- type: Plans
  url: plans/1lookup-plans-pricing.yml
- type: Lifecycle
  url: lifecycle/1lookup-lifecycle.yml
- type: Conformance
  url: conformance/1lookup-conformance.yml
- type: Compliance
  url: https://www.1lookup.io/security
- type: TrustCenter
  url: security/1lookup-trust-center.yml
- type: Security
  url: https://www.1lookup.io/security
- type: VulnerabilityDisclosure
  url: security/1lookup-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/1lookup-domain-security.yml
- type: WellKnown
  url: well-known/1lookup-well-known.yml
- type: Packages
  url: packages/1lookup-packages.yml
- type: Sandbox
  url: sandbox/1lookup-sandbox.yml
- type: MCPServer
  url: mcp/1lookup-mcp.yml
- type: ToolCrosswalk
  url: mcp/1lookup-tool-crosswalk.yml
- type: LLMsTxt
  url: llms/1lookup-llms.txt
- type: AgentSkill
  url: skills/_index.yml
- type: Idempotency
  url: conventions/1lookup-conventions.yml
- type: Webhooks
  url: asyncapi/1lookup-webhooks.yml
- type: DataModel
  url: data-model/1lookup-data-model.yml
- type: Examples
  url: examples/1lookup-examples.yml
x-enrichment:
  date: '2026-08-14'
  status: enriched
  artifacts_added: 5
  artifacts_updated: 14
  pass: local-v1
  note: '1Lookup rewrote its API reference between 2026-08-09 and 2026-08-14: an Idempotency-Key contract on bulk jobs, a
    signed webhook surface, a thirteen-code error registry, X-Request-Id, Retry-After, a four-tier rate-limit model, a versioning
    policy, two new products, and a machine-readable MCP server card at www.1lookup.io/.well-known/mcp/server-card.json. Still
    no OpenAPI and no A2A agent card.'