Email verification APIs you can pay per call

What email verification APIs do

An email verification API evaluates signals about an email address before an application uses it. The response may cover syntax, the domain's mail configuration, a disposable-address flag or a provider's assessment of whether the mailbox can receive mail. Those signals are related, but they answer different questions and should remain separate fields in an agent's decision record.

A form can use a lightweight check to catch a typing mistake. A data import can use a validation result to identify records that need review. A support workflow can ask whether a domain appears to have mail infrastructure. That evidence does not establish that the person who submitted an address controls it. Ownership needs an appropriate challenge flow; a syntactically valid address is not an authenticated identity.

Pay-per-call access lets an agent inspect a single address without assuming that an entire contact dataset needs a monthly plan. The caller should still understand the paid unit. An endpoint can validate one input, consume a batch or return an asynchronous job. Compare those units before projecting the reference quote to a list of records, and check how the provider handles invalid inputs, unknown states and repeated requests.

Avoid reducing the response to one permanent valid-or-invalid label. A domain can accept mail while a mailbox assessment remains unknown. A temporary rejection can change on a later attempt, and a generic risk score can encode the provider's own tradeoffs. Save the observation time, relevant flags and decision rule. That record helps distinguish a corrected typo from a provider change when a user later asks why a record was rejected.

Which outputs the documented endpoints provide

The types below distinguish address checks from narrower domain or disposable-address signals when a documented endpoint exposes them as a separate product. A route that combines syntax, DNS and SMTP signals remains a combined validation product; its description should state which components it advertises. A route that searches for someone's email address is discovery, rather than verification of the supplied address.

Email inbox rental, message sending, document verification and phone validation do not become email verification through a shared gateway name. A general DNS lookup can reveal mail records without claiming to evaluate a mailbox. The task filter keeps explicit validation products and excludes neighboring tools, so a cheap unrelated utility cannot supply a validation price.

Each price is the cheapest endpoint of that service for that kind of data: the same number wherever this page quotes it.

Read negative and unknown outcomes independently. A provider's disposable-domain flag does not prove abuse by a person. A catch-all domain can accept arbitrary recipients without proving that a particular mailbox belongs to the intended contact. A provider can advertise SMTP checks without promising a successful future delivery. Treat source and method descriptions as provider claims, and retain the result categories actually returned rather than deriving extra certainty from the name “verification.”

Compare 8 email verification services

One row per service, ordered by observed paying wallets. The quote belongs to the endpoint named in that row. Primary data types determine the row quote when available; adjacent products keep their own type prices below.

$/CALL is the price of the endpoint named under it: the cheapest individual email validation and deliverability signals endpoint of the service or, for a service without one, its cheapest email verification endpoint. Never the cheapest tool of a gateway. Other kinds of data have their own price in the tables below. EMAIL VERIFICATION ENDPOINTS counts the email verification endpoints out of all the endpoints the service lists. BUYERS 30D counts distinct wallets that paid the whole service on-chain in 30 days, not only its email verification endpoints. "Generalist" marks a gateway that sells more than three unrelated kinds of tools: it is never called the cheapest.

How to choose an email verification endpoint

Match the decision to the evidence

For a form, distinguish an obvious format error from an inconclusive mailbox result. Give a legitimate user a way to correct or review an address instead of silently treating an unknown state as proof of invalidity. For imported data, decide whether risky or disposable flags trigger exclusion, review or a lower-confidence label. Write that policy before choosing the score threshold.

Preserve the submitted address

Follow the endpoint's documented normalization rules. Avoid inventing provider-specific mailbox rewrites from punctuation or capitalization assumptions. Keep the submitted value and any suggested correction separately. A typo suggestion is a proposed change that may name a different recipient; it should not overwrite a customer record without a deliberate acceptance step.

Evaluate a representative list

Include ordinary addresses, malformed inputs, domains without advertised mail records and records expected to remain unknown. Compare the raw flags and reason codes, not just one vendor's top-level verdict. Measure accepted-result coverage and latency for your actual input set. Monitoring uptime tells you whether the service answers its checks, rather than the truth of a mailbox classification.

Match the request to the output

Start with one representative input and a written acceptance criterion. A successful HTTP status is not enough: inspect the fields your application needs, the distinction between missing and negative results, and the provenance supplied with the response. Keep a small reviewed evaluation set that includes ambiguous inputs as well as straightforward examples. Changing a request parameter can change the product and its payment requirement, so preserve those parameters alongside the endpoint name.

Check the operating evidence

The table reports service monitoring, with a median uptime of 100% and a median selected endpoint price of $0.0045. Monitoring latency describes our checks, rather than a benchmark of a complete paid workflow. A request that triggers a larger job may have a different duration. Compare a provider's documented limits with the concurrency, timeout and result size your caller can handle. Record errors separately from empty answers so an outage does not look like a meaningful absence.

Plan changes and retries

Cache according to the provider's terms and the freshness your task needs. Keep a versioned record of input normalization and response mapping so a later provider change can be investigated. Before an automatic retry, decide whether the previous request could have completed and whether repeating it incurs another charge. An agent should have a request budget and an explicit stopping condition, especially when one answer causes follow-up calls. Validate required fields before submitting a payment rather than discovering an invalid input through a long retry loop.

Choose by the job your caller needs to complete

Start with the result your next step can consume. The candidates below come from the same data-type classification as the comparison table. The displayed job quote is the lowest matching type price for that job, with its source endpoint retained.

Individual email validation and deliverability signals

Compare the documented input, returned fields and paid unit for this output. Preserve ambiguity and missing-result states in the caller.

Candidates today, most buyers first: AgentBIT ($0.03/call, generalist, 71 buyers) · IPIntel.ai x402 Tools ($0.004/call, 25 buyers) · Straelo Relay ($0.005/call, 17 buyers) · DOHMAN Machine Services ($0.001/call, 4 buyers) · Crypto Technicals & Web Utilities ($0.002/call, generalist, 3 buyers) · M0 Email Verification ($0.005/call)

Batch email verification

Compare the documented input, returned fields and paid unit for this output. Preserve ambiguity and missing-result states in the caller.

Candidates today, most buyers first: RallyLive Intel ($0.1/call, 5 buyers)

Domain mail configuration and sender deliverability

Compare the documented input, returned fields and paid unit for this output. Preserve ambiguity and missing-result states in the caller.

Candidates today, most buyers first: IPIntel.ai x402 Tools ($0.001/call, 25 buyers) · RallyLive Intel ($0.05/call, 5 buyers) · PitchPilot Outreach API ($0.003/call, generalist, 1 buyer)

What the providers describe

The descriptions below attribute advertised behavior and limitations to the provider. They were reviewed against its public listing and endpoint descriptions captured on October 21, 2026; operating figures and prices are generated from the page model.

DOHMAN Machine Services

DOHMAN describes an email verification evidence route at $0.001. The advertised checks combine syntax, MX, disposable-domain, role-address and other risk signals; its description explicitly says there is no SMTP probe. The useful product is a structured evidence record with reasons, rather than proof that a recipient exists or controls the address. Read unknown and negative flags separately, keep the submitted input and avoid turning domain-level evidence into a mailbox-delivery guarantee.

1 email verification endpoint of 23 · $0.001/call (GET /functions/v1/x402-email-verify-evidence) · Base · uptime 30d 100% · 166 ms · 4 buyers in 30 days

IPIntel.ai x402 Tools

IPIntel's tool package lists an email validation route at $0.004 and a distinct domain-health product at $0.001. The email description advertises syntax, DNS/MX, disposable, role and free-provider checks, with a normalized address, verdict, risk signals and typo suggestions. Domain health inspects MX, SPF and DMARC configuration and returns issues and recommendations. A cheap domain configuration report cannot stand in for a mailbox assessment. Keep a suggested spelling correction separate from the submitted recipient until it is deliberately accepted.

2 email verification endpoints of 10 · $0.004/call (POST /email-validate) · Base · uptime 30d 100% · 256 ms · 25 buyers in 30 days

AgentBIT

AgentBit describes /v1/email/deliverability as a combined email validation product at $0.03. Its documented signals include syntax, mail-domain checks and address-risk indicators. The same gateway offers unrelated research and business-risk products, whose quotes do not describe validation of an email input. Treat a provider verdict as evidence for the application's review policy, and inspect whether a missing signal means unknown, unsupported or negative before rejecting an address.

1 email verification endpoint of 25 · $0.03/call (GET /v1/email/deliverability) · ARB/Base/POL/SOL · uptime 30d 100% · 130 ms · 71 buyers in 30 days

M0 Email Verification

M0 describes email verification and lead validation routes with a validation quote starting at $0.005. Its /v1/lead-validate route lists email syntax, DNS, MX, disposable-domain and role-account checks; the description explicitly says it does not confirm mailbox existence or person identity. Preserve individual reason fields instead of assuming that a top-level verdict authenticates the contact. A validation response is an observation at a point in time; it does not replace a confirmation flow or establish the person's consent to receive a message.

2 email verification endpoints of 3 · $0.005/call (POST /v1/verify-email) · Base · uptime 30d 94.2% · 434 ms · 0 buyers in 30 days

Straelo Relay

Straelo lists /email-validator/basic as an address validation product at $0.005. The description presents basic syntax and domain checks as the evidence returned by that route. Compare those advertised checks with the acceptance rule for a form or import, rather than reading “validator” as a promise of delivery. A result can help decide whether to request a correction, but the application still needs an explicit policy for inconclusive inputs and for preserving the original address.

1 email verification endpoint of 10 · $0.005/call (GET /email-validator/basic) · Base · uptime 30d 100% · 229 ms · 17 buyers in 30 days

Cost per call and at larger volumes

The median selected endpoint costs $0.0045 per call. At an unchanged request shape, 100,000 calls total $450.00. The table multiplies reference quotes so a prototype and a larger workload can be compared on the same basis.

Each service at the price of its main email verification endpoint, the one named in the table above.

The paid unit matters. One request may return a bounded list, inspect one input, start a job or retrieve an existing result. Check that unit before multiplying a quote by your business volume. A second product, a deeper lookup or a retry can add a charge, while no-match and failure handling depend on the provider's terms. A catalog reference quote does not establish the amount for a larger batch or a changed request body.

For a production budget, measure the calls required for an accepted result. Save the endpoint, normalized request, quoted amount and outcome in the job record. This lets you distinguish a low submission price from a low effective cost. Read the payment requirement for the exact input when the provider describes variable pricing; do not substitute a gateway's cheapest unrelated tool.

What the captured 402 establishes

The catalog lists DOHMAN Machine Services at GET /functions/v1/x402-email-verify-evidence, but the stored 402 for that resource advertises POST with a JSON body containing email in extensions.bazaar.info.input. The catalog method and captured input schema disagree. That evidence does not establish the 402 of a bodyless GET, so this page does not pair a GET curl command with the captured payment terms. The service page retains the full stored response under Payment evidence; its advertised POST schema is evidence to inspect, rather than a verified request trace. The catalog reference quote for this method and path is $0.001; it is not a verified quote for a different method or request body.

Read the provider's current input schema before building a request. Keep the requested resource, accepted network, asset and amount together when evaluating its challenge. Stored payment evidence does not show a tested paid answer, establish data accuracy or prove that a background job completed. Inspect the full payload on the linked service page and obtain the challenge for the exact request before authorizing payment.

How to interpret this comparison

The listing requires an online, payment-ready service, a usable description, a known price and at least 90% measured uptime over 30 days. Endpoint selection then keeps routes that describe the page's task. A candidate can match a word in its general description yet be excluded because its documented routes return a different product. These are discovery criteria rather than certification of delivered output.

Provider paragraphs attribute statements read in the public listing and endpoint descriptions captured on October 21, 2026. Source, scope and output claims belong to the provider. x402-list monitoring supplies the price and operating figures; it does not independently establish the correctness of the underlying dataset or a vendor's performance claims.

Buyer counts are distinct paying wallets observed for the service in the measurement window, with the coverage limits described on its service page. They do not count people or prove usage of a particular route. Endpoint prices, data-type counts and job candidates share one endpoint classification. If a service disappears, its generated candidates and token-dependent descriptions disappear with it. Open the methodology and linked service pages before deciding what that evidence means for a recurring workflow.

Questions

How to pay

Each service answers an unpaid call with HTTP 402 and its price; your agent signs a USDC payment on the listed network and retries. No API key, no account, no subscription. See what x402 is.