specification: API Commons Rate Limits
specificationVersion: '0.1'
schema: https://raw.githubusercontent.com/api-evangelist/interface-research/main/schema/api-commons.yml#/$defs/RateLimits
provider: Email Verifier API
providerId: email-verifier-api
created: '2026-05-06'
modified: '2026-05-06'
reconciled: false
tags:
  - Email Verification
  - Deliverability
  - SMTP Check
  - Rate Limiting
description: |-
  Email Verifier API does not publish numeric per-second / per-minute rate limits in its
  v2 documentation. Throttling is enforced through the credit balance: every "Paid"
  verification event consumes one credit, and the response returns the remaining balance
  in the `remaining` field. The free web tool exposes a separate per-user daily allowance
  of 5 verifications. Customers running high-volume traffic should coordinate with the
  vendor through support@emailverifierapi.com to confirm any platform-side throughput
  ceilings.
sources:
  - https://emailverifierapi.com/api-docs/
  - https://emailverifierapi.com/free-email-verifier/
  - https://emailverifierapi.com/pricing/
notes: |-
  Public documentation does not surface a fixed RPS or RPM. The credit balance acts as
  the primary quota control. Sub-500ms typical response time is published as a service
  characteristic but is not a contractual rate limit.
responseCodes:
  throttled: 429
  serviceUnavailable: 503
limits:
  - name: Credit balance (paid events)
    scope: api-key
    metric: credit
    limit: customer balance
    notes: |-
      Each Paid event (mailboxExists, mailboxDoesNotExist, mailboxIsFull) consumes one
      credit. Free events (invalidSyntax, domainDoesNotExist, mxServerDoesNotExist,
      isCatchall, isGreylisting, transientError) do not consume credits. The remaining
      balance is returned on every response in the `remaining` field.
  - name: Free tool daily checks
    scope: visitor
    metric: request
    limit: 5
    timeFrame: day
    notes: |-
      The browser-based free email verifier at /free-email-verifier/ allows 5 checks per
      day per user before requiring registration for the API free tier (100 credits).
  - name: Per-request execution time
    scope: request
    metric: seconds
    limit: 'sub-500ms typical'
    notes: |-
      Published service characteristic. Each response returns an `execution` field with
      the wall-clock duration of the verification, useful for client-side timeout tuning.
policies:
  - name: Credit-First Throttling
    description: |-
      The credit balance is the primary throttle. Monitor the `remaining` field returned
      on every successful response to budget verification work and to top up before
      hitting zero balance.
  - name: Backoff
    description: |-
      Honor 429 (throttled) and 503 (service unavailable) responses with exponential
      backoff and jitter. Retry transient (`status: transient`, `event: transientError`)
      responses after a short delay rather than immediately.
  - name: Auto-Refund
    description: |-
      Credits are not consumed for free events or for requests that fail on syntax / DNS /
      MX. This effectively functions as an auto-refund for non-verifiable inputs.
  - name: High-Volume Coordination
    description: |-
      For sustained high-throughput verification (bulk list cleanup, cron-driven
      reverification), coordinate with support@emailverifierapi.com so that platform-side
      ceilings can be confirmed and lifted if needed.
maintainers:
  - FN: Kin Lane
    email: kin@apievangelist.com