NeverBounce

NeverBounce is an email verification and list cleaning service — a ZoomInfo company — that validates individual email addresses in real time and cleans bulk lists by checking syntax, mailbox existence, role addresses, disposable addresses, catch-all domains, and deliverability to reduce bounce rates for marketing, sales, and transactional senders. The NeverBounce v4 REST API at https://api.neverbounce.com/v4.2/ provides ten published operations covering single email checks (/single/check), bulk list jobs (create, parse, start, status, results, search, delete, download), account credit info, and the Proof-of-Engagement confirmation used by the browser widget, with JSON responses over HTTPS. Authentication uses a per-integration API key (format `secret_xxxx...`) passed as the `key` parameter in the query string or request body; `public_` keys drive the JavaScript widget and cannot call the standard API. Application errors — including authentication failure and throttling — are returned with an HTTP 200 and a `status` field rather than a 4xx, which is the defining runtime quirk of this API.

NeverBounce publishes 5 APIs on the APIs.io network, including Account API, Jobs API, Single API, and 2 more. Tagged areas include Email Verification, Email Hygiene, Deliverability, Marketing, and List Cleaning.

The NeverBounce catalog on APIs.io includes 1 event-driven AsyncAPI specification.

NeverBounce’s developer surface includes authentication, CLI, changelog, documentation, API reference, getting-started guide, pricing, and 29 more developer resources.

🌐 Visit website 📡 Source on GitHub

58.6/100 strong ▬ flat Agent 42/100 agent ready saas Full breakdown ↓
scored 2026-09-25 · rubric v0.23.0

AccessPaidSelf serveFree trial

1 APIs 1 MCP Servers

Email VerificationEmail HygieneDeliverability MarketingList CleaningData QualityZoomInfoEmail

Kin Score

Kin Score How this is scored →
scored 2026-09-25 · rubric v0.23.0

Composite quality — 58.6/100 · strong

Contract Quality 9.9 / 19

Developer Ergonomics 8.1 / 15

Access Clarity 11.4 / 15

Operational Transparency 8.0 / 10

Contract Governance 0.4 / 9

Discoverability 5.6 / 8

Regulatory Posture 3.7 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 42/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

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 applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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 github.com/api-evangelist/neverbounce: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 5

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

NeverBounce API v4

RESTful JSON API for email verification. Provides single email verification (`/single/check`), bulk job verification (`/jobs/create`, `/jobs/parse`, `/jobs/start`, `/jobs/status...

NeverBounce Account API

Account credit balances and job counts by state.

NeverBounce Jobs API

Bulk list verification jobs — create, parse, start, status, results, search, delete, download.

NeverBounce Single API

Real-time verification of a single email address.

NeverBounce POE API

Proof of Engagement. Server-side confirmation that a verification produced by the browser JavaScript widget genuinely came from NeverBounce, using the transaction_id and confirm...

Open Collections 5

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

NeverBounce API v4 Account API

OPEN COLLECTION

NeverBounce API v4 Account Jobs API

OPEN COLLECTION

NeverBounce API v4 Account Single API

OPEN COLLECTION

NeverBounce API v4

OPEN COLLECTION

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

NeverBounce Developer Docs MCP

MCP SERVER

Pricing Plans 1

Published pricing tiers and plan structures.

Neverbounce Plans Pricing

17 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Neverbounce Rate Limits

6 limits

RATE LIMITS

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Neverbounce Webhooks

ASYNCAPI

Security Posture 2

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

Neverbounce Authentication

apiKey · 1 scheme

SECURITY

Neverbounce Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

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

Neverbounce Agentic Access

10 operations · 5 acting

AGENTIC

Resources

Get Started 3

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

Signup

Signup

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 5

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

MCPServer

AgentSkill

LLMsTxt

LlmsText

Design & Contract 7

Pagination, idempotency, versioning, errors, and events

Components

Conventions

ErrorCatalog

DataModel

Conformance

Lifecycle

Webhooks

Scroll for all 7

Build 5

SDKs, sample code, and the tooling you integrate with

Packages

SDKs

CLI

ToolCrosswalk

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 5

Status, limits, changes, and where to get help

Deprecation

StatusPage

ChangeLog

RateLimits

Support

Commercial 4

Pricing, plans, and the legal terms of use

Plans

Pricing

TermsOfService

PrivacyPolicy

Company 3

The organization behind the API

LinkedIn

Website

Website

Blog

Blog

Source (apis.yml)

aid: neverbounce
name: NeverBounce
description: NeverBounce is an email verification and list cleaning service — a ZoomInfo company — that validates individual
  email addresses in real time and cleans bulk lists by checking syntax, mailbox existence, role addresses, disposable addresses,
  catch-all domains, and deliverability to reduce bounce rates for marketing, sales, and transactional senders. The NeverBounce
  v4 REST API at https://api.neverbounce.com/v4.2/ provides ten published operations covering single email checks (/single/check),
  bulk list jobs (create, parse, start, status, results, search, delete, download), account credit info, and the Proof-of-Engagement
  confirmation used by the browser widget, with JSON responses over HTTPS. Authentication uses a per-integration API key (format
  `secret_xxxx...`) passed as the `key` parameter in the query string or request body; `public_` keys drive the JavaScript
  widget and cannot call the standard API. Application errors — including authentication failure and throttling — are returned
  with an HTTP 200 and a `status` field rather than a 4xx, which is the defining runtime quirk of this API.
type: Index
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: paid
  onboarding: self-serve
  trial: true
  try_now: false
  public: true
  label: Self-serve signup with published per-credit pricing
  confidence: high
  source:
  - authentication
  - plans/neverbounce-plans-pricing.yml
  - https://www.neverbounce.com/pricing
  generated: '2026-08-13'
  method: searched
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/neverbounce.png
tags:
- Email Verification
- Email Hygiene
- Deliverability
- Marketing
- List Cleaning
- Data Quality
- ZoomInfo
- Email
tags_raw:
- Email Verification
- Email Validation
- Email Hygiene
- Deliverability
- Marketing
- List Cleaning
- Data Quality
- ZoomInfo
- Email
url: https://raw.githubusercontent.com/api-evangelist/neverbounce/refs/heads/main/apis.yml
created: '2026-05-11'
modified: '2026-08-13'
specificationVersion: '0.23'
apis:
- aid: neverbounce:v4-api
  name: NeverBounce API v4
  description: RESTful JSON API for email verification. Provides single email verification (`/single/check`), bulk job verification
    (`/jobs/create`, `/jobs/parse`, `/jobs/start`, `/jobs/status`, `/jobs/results`, `/jobs/search`, `/jobs/delete`, `/jobs/download`),
    account credit info, and Proof-of-Engagement (`/poe/confirm`) endpoints. GET and POST are interchangeable; PUT and DELETE
    are unsupported. Authentication uses a per-integration API key (`secret_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx`) passed via
    the `key` query/body parameter.
  humanURL: https://developers.neverbounce.com/docs/api-getting-started
  baseURL: https://api.neverbounce.com/v4
  tags:
  - Email Verification
  - REST
  - JSON
  - Deliverability
  properties:
  - type: Documentation
    url: https://developers.neverbounce.com/docs/api-getting-started
  - type: APIReference
    url: https://developers.neverbounce.com/reference/getting-started
  - type: Verifying an Email
    url: https://developers.neverbounce.com/docs/verifying-an-email
  - type: Verifying a List
    url: https://developers.neverbounce.com/docs/verifying-a-list
  - type: GitHub SDKs
    url: https://github.com/NeverBounce
- aid: neverbounce:neverbounce-account-api
  name: NeverBounce Account API
  description: Account credit balances and job counts by state.
  humanURL: https://developers.neverbounce.com/reference/account-info
  baseURL: https://api.neverbounce.com/v4
  tags:
  - Account
  properties:
  - type: OpenAPI
    url: openapi/neverbounce-account-api-openapi.yml
  - type: Overlay
    url: overlays/neverbounce-account-overlay.yaml
- aid: neverbounce:neverbounce-jobs-api
  name: NeverBounce Jobs API
  description: Bulk list verification jobs — create, parse, start, status, results, search, delete, download.
  humanURL: https://developers.neverbounce.com/reference/jobs
  baseURL: https://api.neverbounce.com/v4
  tags:
  - Job
  tags_raw:
  - Jobs
  properties:
  - type: OpenAPI
    url: openapi/neverbounce-jobs-api-openapi.yml
  - type: Overlay
    url: overlays/neverbounce-jobs-overlay.yaml
  - type: Webhooks
    url: asyncapi/neverbounce-webhooks.yml
- aid: neverbounce:neverbounce-single-api
  name: NeverBounce Single API
  description: Real-time verification of a single email address.
  humanURL: https://developers.neverbounce.com/reference/single-check
  baseURL: https://api.neverbounce.com/v4
  tags:
  - Single
  properties:
  - type: OpenAPI
    url: openapi/neverbounce-single-api-openapi.yml
  - type: Overlay
    url: overlays/neverbounce-single-overlay.yaml
- aid: neverbounce:neverbounce-poe-api
  name: NeverBounce POE API
  description: Proof of Engagement. Server-side confirmation that a verification produced by the browser JavaScript widget
    genuinely came from NeverBounce, using the transaction_id and confirmation_token the widget issues.
  humanURL: https://developers.neverbounce.com/reference/widget-poe-confirm
  baseURL: https://api.neverbounce.com/v4
  tags:
  - POE
  - Widgets
  tags_raw:
  - POE
  - Widget
  properties:
  - type: OpenAPI
    url: openapi/neverbounce-poe-api-openapi.yml
  - type: Overlay
    url: overlays/neverbounce-poe-overlay.yaml
common:
- type: AgenticAccess
  url: agentic-access/neverbounce-agentic-access.yml
- type: DomainSecurity
  url: security/neverbounce-domain-security.yml
- type: Authentication
  url: authentication/neverbounce-authentication.yml
- type: Packages
  url: packages/neverbounce-packages.yml
- type: SDKs
  url: packages/neverbounce-packages.yml
- type: CLI
  url: cli/neverbounce-cli.yml
- type: Components
  url: components/neverbounce-components.yml
- type: Conventions
  url: conventions/neverbounce-conventions.yml
- type: ErrorCatalog
  url: errors/neverbounce-problem-types.yml
- type: DataModel
  url: data-model/neverbounce-data-model.yml
- type: Conformance
  url: conformance/neverbounce-conformance.yml
- type: Lifecycle
  url: lifecycle/neverbounce-lifecycle.yml
- type: Deprecation
  url: lifecycle/neverbounce-lifecycle.yml
- type: StatusPage
  url: https://status.neverbounce.com
- type: ChangeLog
  url: changelog/neverbounce-changelog.yml
- type: Plans
  url: plans/neverbounce-plans-pricing.yml
- type: RateLimits
  url: rate-limits/neverbounce-rate-limits.yml
- type: Webhooks
  url: asyncapi/neverbounce-webhooks.yml
- type: MCPServer
  url: mcp/neverbounce-mcp.yml
- type: ToolCrosswalk
  url: mcp/neverbounce-tool-crosswalk.yml
- type: AgentSkill
  url: skills/_index.yml
- type: LLMsTxt
  url: llms/neverbounce-llms.txt
- type: LlmsText
  url: https://developers.neverbounce.com/llms.txt
- type: LinkedIn
  url: https://www.linkedin.com/company/neverbounce
- type: Website
  url: https://www.neverbounce.com
- type: Documentation
  url: https://developers.neverbounce.com/
- type: DeveloperPortal
  url: https://developers.neverbounce.com/
- type: APIReference
  url: https://developers.neverbounce.com/reference/getting-started
- type: GettingStarted
  url: https://developers.neverbounce.com/docs/api-getting-started
- type: GitHubOrganization
  url: https://github.com/NeverBounce
- type: Pricing
  url: https://www.neverbounce.com/pricing
- type: Signup
  url: https://app.neverbounce.com/register
- type: Support
  url: https://www.neverbounce.com/contact
- type: Blog
  url: https://www.neverbounce.com/blog
- type: TermsOfService
  url: https://www.neverbounce.com/terms-of-use
- type: PrivacyPolicy
  url: https://www.zoominfo.com/legal/privacy-policy
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
x-enrichment:
  date: '2026-08-13'
  status: enriched
  artifacts_added: 26
  pass: local-v1

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