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FirstSales pricing and alternatives: email verification API

FirstSales's sitellms.txtBest email verification API in 2026

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33% complete: 2 of the 6 key fields we checkSee the 6 fields
$0.00per 1,000 emailsHalf of the 2,475 plans we rank by price cost $2.00 per 1,000 emails or less. This plan and 7 others tie for the lowest price per 1,000 emails of the 2,475 plans.Enrich.so, GetProspect and treg are the best email verification API providers in our benchmark.
Plan: Public, no key FirstSales's only plan
Call: POST /api/v1/email/validate FirstSales's only call
API: Email verification API FirstSales's only API

About this item

  • Stored. FirstSales may skip the mail server and answer from stored data. FirstSales doesn't say how old the data is.
  • 2 of the 6 key fields we check. Deliverability, Company.
  • Nothing to pay. You get up to 864,000 calls a month.
  • One call. You send email to POST /api/v1/email/validate. The call returns whether the address takes mail.
  • Who can get it: anyone at least 18 years old, for B2B commercial use only. Keep data: no limit. Use data: with conditions.

FirstSales: email verification API alternatives

We list other providers' plans closest to this plan in price per 1,000 emails. Each plan in the table gives stored data.

This planFirstSales, freeKaijuVerifier, free, POST /api/v1/jobs, Submit an async bulk jobMailSift, free, GET /verify, Verify one emailByteplant, free trial, POST /api/bulk-verifyEasyEmailAPI, freeInterzoid, free API key, POST /enrich
$ per 1,000 emails$0.00$0.00$0.00$0.00$0.00$0.00
Completeness33%50%67%17%67%50%
Billingfreefreefreefreefreefree
Pay$0$0$0$0$0$0
Enough for864,000 calls a month100 results a month500 calls, once1,000 results, once5,000 calls a monthnot published
Freshnessstoredstoredstored (MX, SPF, DMARC: live)storedstored (valid MX, MX: live)stored
Who can get itanyone at least 18 years old, for B2B commercial use onlyanyoneanyone 16 or olderbusinesses and professionals with a business email, once eachanyoneanyone

Every email verification API provider we score, ranked

Sources

From each provider's own pricing page and docs, and from what providers tell us. We read this row from these pages on 2026-10-23.

  1. firstsales.io/api/llms.txt
  2. firstsales.io/developers.md
  3. firstsales.io/developers/
  4. firstsales.io/llms.txt
  5. firstsales.io/openapi.json
  6. firstsales.io/pricing.md
  7. firstsales.io/pricing/
  8. firstsales.io/terms-of-service/

Product details

The key fields this plan's answer can hold, then each filled column in its row on the sheet.

  • Address, not in the answer
  • Deliverability
  • Confidence, not in the answer
  • Name, not in the answer
  • Place, not in the answer
  • Company
Score
Overall score0.0. We give it 0 overall because its Data score is 0.
Price score100
Data score0
Cost to get started score100
Bundle score95
Performance score0. We could not measure how fast this provider answers a call, so we count it as 0.
Price
$ per 1,000 emails$0.00
Percall
Billingfree
Aggregators
Aggregatorsnone
Charges
Also pays forScore an email domain for disposable/temporary-mailbox risk · Detect whether a domain accepts mail to any mailbox (catch-all) · Run one specific DNS/email-authentication/security check against a domain · Look up and validate a domain's DKIM record · Run SPF, DKIM, DMARC, and MX checks together with a confidence score · Reverse-DNS (PTR) lookup for an IPv4 address, with forward-confirmation · Get a domain's registration age and expiration via RDAP · Fetch every DNS record type for a domain in one call · Discover subdomains via Certificate Transparency logs · Score email content for spam-trigger risk · Score and improve a cold-email subject line · Grade a full cold-email draft across 8 deliverability/effectiveness dimensions · Score and improve a cold-email body · Detect and score personalization signals in cold-email content · Create a temporary test inbox · Read the received emails for a test inbox · List public tutorials · Get one tutorial by slug · Service health check
Not found
$ per 1,000$0.00
In their words
Their pitchCheck email addresses, DNS records and cold email copy from your own code, with no key.
Data
Freshnessstored
Keep datano limit
Use dataYou agree to use the Service only for lawful B2B commercial outreach, and to follow all laws and regulations that apply. You must not do any of the following: [...] Resell, sublicense or white-label the Service, or make it available to anyone else, without written permission from FirstSales first. [...] Use automated scripts, bots or other tools to put artificial load on, overload or interfere with the Service's systems or the systems of mailbox providers. [...] Get around or turn off any rate limits, sending caps or security controls built into the Service.
Plan
Pay$0
Enough for864,000 calls a month
Rate limit
Per second0.33
Batch1
Speed
Answerin the call
The call
You sendemail
MethodPOST
Path/api/v1/email/validate
About the plan
PlanPublic, no key
Who can get itanyone at least 18 years old, for B2B commercial use only
The 11 fields the plan's answer can hold

valid, domain, domain exists, has MX record, reserved domain, disposable, free provider, MX records, MX priority, error, message

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