FirstSales

FirstSales provides an AI‑powered cold email platform that lets users send unlimited cold emails from multiple mailboxes. The service includes AI agents that can find leads, draft personalized messages, and handle follow‑ups, as well as a warm‑up feature to improve deliverability. Pricing starts at $29 per month, and the platform integrates with popular CRMs and email providers. It aims to help sales teams scale outreach efficiently while maintaining compliance and deliverability best practices.

FirstSales publishes 7 API contracts indexed on the APIs.io network, including Analyze API, DNS API, Domain API, and 4 more. Tagged areas include AI outbound sales, Cold Email, Email Warm-up, and Lead Generation.

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

FirstSales’ developer surface includes CLI, changelog, authentication, getting-started guide, documentation, API reference, engineering blog, and 24 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

52.2/100 developing Agent 64/100 agent native Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

AccessPaidApproval

1 published contract 1 Agent Skills

AI outbound salesCold Email Email Warm-up Lead Generation

Kin Score

Kin Score How this is scored →
scored 2026-11-13 · rubric v0.28.0

Composite quality — 52.2/100 · developing

Contract Quality 13.1 / 21

Developer Ergonomics 10.4 / 17

Access Clarity 8.7 / 17

Operational Transparency 3.7 / 11

Contract Governance 2.2 / 10

Discoverability 5.8 / 9

Regulatory Posture 2.8 / 15

Agent readiness — 64/100 · agent native

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 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 0 / 6

Agent Skills 5 / 5

Well-Known Catalog 4 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 8 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 6 / 6

Protected Resource Metadata 5 / 5

Registration Without a Human 6 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 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 could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% 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 Ask about this →
Typed Event Surface +6 pts — AsyncAPI document, OR webhooks/callbacks objects in the as-published OpenAPI, OR common[].type includes Webhooks Ask about this →
Documented Reversibility +6 pts — a reversal operation in the contract, graded up when a window is documented too Ask about this →
Agentic Commerce Well-Known Document +5 pts — a parsing /.well-known/ucp.json or acp.json declaring a version and at least one service, OR (0.27) a live x402 payment challenge from _data/x402-adoption.json — `self` when its endpoints are on the provider's own domain, `platform` when they are on a vendor's Ask about this →
Dry-Run / Simulate Mode +4 pts — OpenAPI: destructive operations expose a dry_run / simulate / preview / validate_only parameter Ask about this →
Consent & Bot Identity +3 pts — common[].type includes AIPREF, ContentSignal, WebBotAuth, or HTTPMessageSignatures Ask about this →

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

Access Clarity scores 51.1 — up to +9.8 composite points Ask about this →
Contract Quality scores 61.7 — up to +9.6 composite points Ask about this →
Contract Governance scores 22.0 — up to +9.4 composite points Ask about this →

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.

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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/firstsales-io/apis.yml: open an issue on github.com/api-evangelist/firstsales-io 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 4

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.

Agent2Agent

measured — observed by APIs.io (conformant)

OAuth 2.0 Protected Resource Metadata

measured — observed by APIs.io (verified)

Dynamic Client Registration

measured — observed by APIs.io (published)

OpenAPI

measured — observed by APIs.io (published)

APIs 7

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

FirstSales Analyze API

AI-assisted cold-email content analysis.

FirstSales DNS API

DNS record and deliverability diagnostics.

FirstSales Domain API

Domain intelligence (age, records, subdomains).

FirstSales Email API

Email address validation and risk checks.

FirstSales Mail Tester API

Temporary test inbox and received-email analysis.

FirstSales System API

Service health.

FirstSales Tutorials API

Public, no-auth tutorial content feed.

Scroll for all 7

Agent Skills 1

Packaged agent skills for driving this provider's APIs from an AI assistant.

analyze-cold-email

AGENT SKILL

FirstSales API pricing

Prices published by FirstSales, read 2026-11-08 from docs.firstsales.io/plans.

Plan	Price
Plan 1	$35
Plan 2	$85
Plan 3	$169
Plan 4	$255
Plan 5	$339
Plan 6	$425
Plan 7	$509
Plan 8	$589

All 21 plans, limits and sources →

Rate limits

general authenticated requests: 600 per minute
whoami endpoint: 60 per minute

Rate-limit details →

Pricing Plans 1

Published pricing tiers and plan structures.

FirstSales Plans Pricing

21 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

FirstSales Rate Limits

2 limits

RATE LIMITS

Semantic Vocabularies 1

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

Firstsales Io Context

20 classes · 78 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs. Counts are the severity each rule declares, not results of running them.

FirstSales API Rules

68 rules · 61 error-severity 6 warn-severity 1 info-severity

SPECTRAL

JSON Schema 7

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

ColdEmailAnalysisResult

8 properties

JSON SCHEMA

DisposableCheckResult

4 properties

JSON SCHEMA

DkimResult

9 properties

JSON SCHEMA

DomainAgeResult

10 properties

JSON SCHEMA

HealthResponse

3 properties

JSON SCHEMA

PersonalizationAnalysisResult

6 properties

JSON SCHEMA

PublicTutorial

10 properties

JSON SCHEMA

Scroll for all 7

Security Posture 2

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

FirstSales Authentication

1 scheme

SECURITY

FirstSales Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access (API Evangelist recommendations) 1

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

FirstSales Agentic Access

20 operations · 11 acting

AGENTIC

Resources

Get Started 2

Portal, sign-up, and the first successful call

GettingStarted

GettingStarted

DeveloperPortal

DeveloperPortal

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgentSkill

LLMsTxt

WellKnown

Design & Contract 8

Pagination, idempotency, versioning, errors, and events

Spectral

JSONLD

Vocabulary

DataModel

Idempotency

Conventions

ErrorCatalog

Conformance

Scroll for all 8

Build 1

SDKs, sample code, and the tooling you integrate with

CLI

CLI

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 3

Status, limits, changes, and where to get help

RateLimits

RateLimits

ChangeLog

ChangeLog

ChangeLog

ChangeLog

Commercial 4

Pricing, plans, and the legal terms of use

Plans

Pricing

PrivacyPolicy

TermsOfService

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 3

Properties that don't map to a standard resource type

AgentCard

AgentCard

Hosts

Hosts

Vendors

Vendors

Source (apis.yml)

aid: firstsales-io
name: FirstSales
accessModel:
  pricing: paid
  onboarding: approval
  trial: false
  try_now: false
  public: false
  label: Paid · Requires approval
  confidence: high
  source:
  - plans
  - authentication
  - rate-limits
  - security
  generated: '2026-11-13'
  method: derived
image: https://firstsales.io/og/?title=Your+AI+SDR+Books+Meetings+on+Autopilot+%7C+FirstSales&eyebrow=AI+SDR+PLATFORM&l=en&v=1&p=home&s=OfyenVW_d_c-OYMbQRFayawQgXZppN57s86aS0ALBIo
description: FirstSales provides an AI‑powered cold email platform that lets users send unlimited cold emails from multiple
  mailboxes. The service includes AI agents that can find leads, draft personalized messages, and handle follow‑ups, as well
  as a warm‑up feature to improve deliverability. Pricing starts at $29 per month, and the platform integrates with popular
  CRMs and email providers. It aims to help sales teams scale outreach efficiently while maintaining compliance and deliverability
  best practices.
url: https://artifacts.apis.io/firstsales-io/apis.yml
x-type: company
x-source: harvest:mcp-registry
x-tier: profiled
x-tier-reason: enrichment pass 2026-11-08 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-11-08'
modified: '2026-11-08'
tags:
- AI outbound sales
- Cold Email
- Email Warm-up
- Lead Generation
tags_raw:
- AI outbound sales
- Cold email
- Email warm‑up
- Lead generation
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: AgenticAccess
  url: agentic-access/firstsales-io-agentic-access.yml
- type: RateLimits
  url: rate-limits/firstsales-io-rate-limits.yml
- type: Plans
  url: plans/firstsales-io-plans-pricing.yml
- type: Spectral
  url: rules/firstsales-io-rules.yml
- type: JSONLD
  url: json-ld/firstsales-io-context.jsonld
- type: Vocabulary
  url: vocabulary/firstsales-io-vocabulary.yml
- type: AgentSkill
  url: skills/_index.yml
- type: DataModel
  url: data-model/firstsales-io-data-model.yml
- type: CLI
  url: cli/firstsales-io-cli.yml
- type: ChangeLog
  url: changelog/firstsales-io-changelog.yml
- type: Idempotency
  url: conventions/firstsales-io-conventions.yml
- type: Conventions
  url: conventions/firstsales-io-conventions.yml
- type: Authentication
  url: authentication/firstsales-io-authentication.yml
- type: ErrorCatalog
  url: errors/firstsales-io-problem-types.yml
- type: Conformance
  url: conformance/firstsales-io-conformance.yml
- type: LLMsTxt
  url: llms/firstsales-io-llms.txt
- type: AgentCard
  url: a2a/firstsales-io-a2a.yml
- type: WellKnown
  url: well-known/firstsales-io-well-known.yml
- type: Hosts
  url: hosts/firstsales-io-hosts.yml
- type: Vendors
  url: vendors/firstsales-io-vendors.yml
- type: GettingStarted
  url: https://developer.firstsales.io/docs/quickstart
- type: Documentation
  url: https://developer.firstsales.io/
- type: DeveloperPortal
  url: https://developer.firstsales.io\
- type: DomainSecurity
  url: security/firstsales-io-domain-security.yml
- type: Website
  url: https://firstsales.io/
- type: APIReference
  url: https://developer.firstsales.io/api-reference/introduction
- type: Blog
  url: https://firstsales.io/blog/
- type: ChangeLog
  url: https://firstsales.io/changelog/
- type: Pricing
  url: https://firstsales.io/pricing/
- type: PrivacyPolicy
  url: https://firstsales.io/privacy-policy/
- type: TermsOfService
  url: https://firstsales.io/terms-of-service/
apis:
- aid: firstsales-io:firstsales-io-analyze-api
  name: FirstSales Analyze API
  description: AI-assisted cold-email content analysis.
  humanURL: https://developer.firstsales.io/api-reference/introduction
  baseURL: https://firstsales.io
  tags:
  - Analyze
  properties:
  - type: OpenAPI
    url: openapi/firstsales-io-analyze-api-openapi.yml
  - type: JSONSchema
    url: json-schema/firstsales-io-cold-email-analysis-result-schema.json
  - type: JSONSchema
    url: json-schema/firstsales-io-personalization-analysis-result-schema.json
- aid: firstsales-io:firstsales-io-dns-api
  name: FirstSales DNS API
  description: DNS record and deliverability diagnostics.
  humanURL: https://developer.firstsales.io/api-reference/introduction
  baseURL: https://firstsales.io
  tags:
  - DNS
  properties:
  - type: OpenAPI
    url: openapi/firstsales-io-dns-api-openapi.yml
  - type: JSONSchema
    url: json-schema/firstsales-io-dkim-result-schema.json
- aid: firstsales-io:firstsales-io-domain-api
  name: FirstSales Domain API
  description: Domain intelligence (age, records, subdomains).
  humanURL: https://developer.firstsales.io/api-reference/introduction
  baseURL: https://firstsales.io
  tags:
  - Domain
  properties:
  - type: OpenAPI
    url: openapi/firstsales-io-domain-api-openapi.yml
  - type: JSONSchema
    url: json-schema/firstsales-io-domain-age-result-schema.json
- aid: firstsales-io:firstsales-io-email-api
  name: FirstSales Email API
  description: Email address validation and risk checks.
  humanURL: https://developer.firstsales.io/api-reference/introduction
  baseURL: https://firstsales.io
  tags:
  - Email
  properties:
  - type: OpenAPI
    url: openapi/firstsales-io-email-api-openapi.yml
  - type: JSONSchema
    url: json-schema/firstsales-io-disposable-check-result-schema.json
- aid: firstsales-io:firstsales-io-mail-tester-api
  name: FirstSales Mail Tester API
  description: Temporary test inbox and received-email analysis.
  humanURL: https://developer.firstsales.io/api-reference/introduction
  baseURL: https://firstsales.io
  tags:
  - Mail Tester
  properties:
  - type: OpenAPI
    url: openapi/firstsales-io-mail-tester-api-openapi.yml
- aid: firstsales-io:firstsales-io-system-api
  name: FirstSales System API
  description: Service health.
  humanURL: https://developer.firstsales.io/api-reference/introduction
  baseURL: https://firstsales.io
  tags:
  - System
  properties:
  - type: OpenAPI
    url: openapi/firstsales-io-system-api-openapi.yml
  - type: JSONSchema
    url: json-schema/firstsales-io-health-response-schema.json
- aid: firstsales-io:firstsales-io-tutorials-api
  name: FirstSales Tutorials API
  description: Public, no-auth tutorial content feed.
  humanURL: https://developer.firstsales.io/api-reference/introduction
  baseURL: https://firstsales.io
  tags:
  - Tutorials
  properties:
  - type: OpenAPI
    url: openapi/firstsales-io-tutorials-api-openapi.yml
  - type: JSONSchema
    url: json-schema/firstsales-io-public-tutorial-schema.json
x-enrichment:
  date: '2026-11-08'
  status: enriched
  artifacts_added: 37
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

FirstSales API — frequently asked questions

Does FirstSales have an API?

Yes. APIs.io lists 7 APIs from FirstSales, including FirstSales Analyze API, FirstSales DNS API and FirstSales Domain API, and 4 more.

Is there an OpenAPI specification for the FirstSales API?

Yes. APIs.io indexes 7 OpenAPI specifications for FirstSales, each linked for download from this page.

How do I authenticate with the FirstSales API?

FirstSales documents its authentication (1 scheme). The details are profiled on APIs.io as FirstSales Authentication.

How much does the FirstSales API cost?

FirstSales publishes its prices; its Plan 1 plan is $35 as of 2026-11-08. APIs.io lists 21 pricing plans for FirstSales, with each plan's price, limits and inclusions under Pricing on this page.

Is the FirstSales API ready for AI agents?

FirstSales has a Kin Score of 52.2 out of 100 (developing) and an Agent Readiness score of 63.6 (agent-native), scored by API Evangelist on 2026-11-13.

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