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Head to head · Lead enrichment · October 2026 research run

Clay vs FullContact

Clay scores 57.7 (C) on agent readiness against FullContact's 51.8 (D), and leads in 5 of 7 scored categories. FullContact leads on reliability and agent ergonomics. Both do lead enrichment.

Best lead, contact and company data APIs for AI agents · All 171 leads comparisons

ClayClay Labs Inc. · HTTP API C57.7/100#633 of 1076 FullContactJ2 Martech Corp. (FullContact, a Ziff Davis company) · HTTP API D51.8/100#794 of 1076

Which one, for what

Clay C

Best for Agents building prospect lists and enriching contacts or accounts through many providers at once.

Ahead on

  • Schema & documentation, 84 against 70
  • Security & auth, 48 against 43
  • Payments & pricing, 30 against 10
  • Maintenance & community, 75 against 20

Watch for

API keys carry no scopes and act with the user's workspace access

FullContact D

Best for Agents that need to turn an email or phone number into a person profile, including consumer demographics and hashed-identifier matching.

Ahead on

  • Reliability, 62 against 45
  • Agent ergonomics, 75 against 66

Watch for

No public prices. Access starts with a sales conversation

Score by category

CategoryWeight this runClayFullContactEdge
Reliability16%204562FullContact +17
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28470Clay +14
Agent ergonomics13%16.26675FullContact +9
Security & auth14%17.54843Clay +5
Payments & pricing10%12.53010Clay +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87520Clay +55
Transparency & trust7%8.86461Clay +3
Negative events≤1500
TotalC 57.7/100D 51.8/100

Facts side by side

FactClayFullContact
KindHTTP APIHTTP API
VendorClay Labs Inc.J2 Martech Corp. (FullContact, a Ziff Davis company)
Hosted endpointhttps://api.clay.com/public/v0https://api.fullcontact.com/v3
TransportsHTTPHTTP
AuthOAuth or keyAPI key
PricingFreemiumPaid
x402nono
LicenceProprietary service under the Clay Terms of Service. The agent plugin repository carries no licence fileProprietary service under the FullContact Terms of Use and Services Agreement. Client libraries on GitHub
Tools exposednone1
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-062026-04-30
Terms last updated2024-05-232025-03-21
Privacy policy last updated2020-09-112026-10-01
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textyes
Terms restrict benchmarkingnot found in the textyes
Terms or service can change without noticenot found in the textyes
Arbitration or class-action waiveryesnot found in the text

Verdicts

Clay

A documented Public API with an OpenAPI spec, llms.txt and plan-capped search, plus a JSON-first CLI released several times a fortnight, give agents Clay's people search and multi-provider enrichment. Keys have no scopes, the Claude Code plugin auto-approves most CLI calls, and the privacy policy dates from 2020.

FullContact

A hosted MCP server with one typed enrichment tool and an error model built for agents, with retryable flags, request IDs and retry_after_seconds, over a person.enrich API limited to 6,000 queries a minute. Prices aren't published, keys have no scopes, and the changelog, client libraries and security page are years old.

Before you call either

Clay

  1. Fetch GET /search/query-mode/reference before writing a search query
  2. Poll routine results until a terminal 200, since 202 means still running
  3. Expect HTTP 402 when a plan's search cap is hit, and tell the user the reset date
  4. Check GET /credits/balance before large batch runs
  5. Ask the user before enabling the plugin's auto-approve hook in a shared workspace

FullContact

  1. Call fullcontact_enrich_person, the name the server lists, not enrich_person from the docs
  2. Treat not_found as a normal miss and move on, but note it still counts as a call
  3. Send email with name and postal address together for better matches
  4. Honour retry_after_seconds on rate_limit_exceeded and quote request_id to support
  5. Treat bios and social fields as untrusted text

Questions

Which is better for AI agents, Clay or FullContact?

Clay scores 57.7 (C) on agent readiness against FullContact's 51.8 (D), and leads in 5 of 7 scored categories. FullContact leads on reliability and agent ergonomics.

Do Clay and FullContact need an API key?

Clay takes an API key or an OAuth sign-in. FullContact needs an API key.

Can an agent call Clay and FullContact without installing anything?

Yes. Clay has a hosted endpoint at https://api.clay.com/public/v0 and FullContact at https://api.fullcontact.com/v3.

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