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 API contracts indexed 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 and 1 Spectral governance ruleset.

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

🌐 Visit website 📡 Profile data on GitHub

65.7/100 strong ▬ flat Agent 45/100 agent ready Heartbeat 16/100 dormant saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessPaidSelf serveFree trial

1 published contract 1 MCP Servers 3 Agent Skills

Email VerificationEmail HygieneDeliverability Marketing List Cleaning Data QualityZoomInfoEmail

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 65.7/100 · strong

Contract Quality 9.9 / 19

Developer Ergonomics 11.0 / 15

Access Clarity 12.6 / 15

Operational Transparency 8.0 / 10

Contract Governance 1.6 / 9

Discoverability 5.6 / 8

Regulatory Posture 3.7 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 45/100 · 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

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 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/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document
Delegated User Identity +6 pts — a served discovery document listing authorization_code in grant_types_supported (served), else an oauth2 authorizationCode flow or openIdConnect declared in an OpenAPI (documented)
Documented Reversibility +6 pts — a reversal operation in the contract, graded up when a window is documented too
Protected Resource Metadata +5 pts — a served /.well-known/oauth-protected-resource carrying `resource` (documented), and naming its authorization_servers (verified)

4 more unmet checks in the Agent Readiness table above.

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

Contract Quality scores 52.8 — up to +11.8 composite points
Contract Governance scores 18.2 — up to +9.8 composite points
Developer Ergonomics scores 73.2 — up to +5.4 composite points

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.

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/neverbounce/apis.yml: open an issue on github.com/api-evangelist/neverbounce 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 →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
Intercom App Store (customer-support, chat and messaging integrations)	builds-on	29.1	-	-

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Standards implemented 2

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.

Model Context Protocol (MCP)

measured — observed by APIs.io (verified)

OpenAPI

measured — observed by APIs.io (published)

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 4

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

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

Remote MCP server at developers.neverbounce.com.

MCP SERVER

Agent Skills 3

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

neverbounce-check-credits-and-usage

AGENT SKILL

neverbounce-verify-a-list

AGENT SKILL

neverbounce-verify-single-email

AGENT SKILL

NeverBounce API pricing

Prices published by NeverBounce, read 2026-10-28 from www.neverbounce.com/pricing.

Plan	Price
Pay as you go	$8/ 1,000 credits Includes: 1,000 / 0.008 per credit; Credits expire 12 months after purchase.
Growth	$49/ month Includes: Up to 10,000 email volume to verify; 200 new leads/month
Enterprise	Custom Includes: Typically used for 250,000+ emails per month

Plan details, limits and sources →

Rate limits

: 10 concurrent
: 50 1d
: 10 1h

All 6 limits →

Billed by: 1,000 credits · FinOps profile →

Pricing Plans 2

Published pricing tiers and plan structures.

Neverbounce Plans Pricing

3 plans

PLANS

Neverbounce Price Estimates

0 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Neverbounce Rate Limits

6 limits

RATE LIMITS

Service Levels 1

Uptime the provider promises or reports, as SLA4OAI. Read from its own pages; APIs.io runs no monitors.

NeverBounce

SLA

FinOps 1

Cost, billing, and metering signals for API financial operations.

Neverbounce Finops

FINOPS

Event Specifications 1

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

Neverbounce Webhooks

ASYNCAPI

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

NeverBounce API Rules

45 rules · 43 errors 1 warnings 1 info

SPECTRAL

OpenAPI Overlays 4

Overlays applied on top of this provider's contracts. Each card says who wrote it: a document the provider publishes, or one API Evangelist derived or generated.

Neverbounce Account Overlay

4 actions · documentation · neverbounce-account-api-openapi.yml

GENERATED

Neverbounce Jobs Overlay

7 actions · documentation · neverbounce-jobs-api-openapi.yml

GENERATED

Neverbounce Poe Overlay

4 actions · documentation · neverbounce-poe-api-openapi.yml

GENERATED

Neverbounce Single Overlay

4 actions · documentation · neverbounce-single-api-openapi.yml

GENERATED

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
x-docs-platform: readme
x-docs-platform-confidence: high
x-docs-platform-checked: 2026-10-04
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

NeverBounce API — frequently asked questions

Does NeverBounce have an API?

Yes. APIs.io lists 5 APIs from NeverBounce, including NeverBounce API v4, NeverBounce Account API and NeverBounce Jobs API, and 2 more.

Is there an OpenAPI specification for the NeverBounce API?

Yes. APIs.io indexes 4 OpenAPI specifications for NeverBounce, each linked for download from this page.

How do I authenticate with the NeverBounce API?

NeverBounce uses bearer-token authentication (apiKey · 1 scheme). The details are profiled on APIs.io as Neverbounce Authentication.

How much does the NeverBounce API cost?

NeverBounce publishes its prices; its Pay as you go plan is $8/ 1,000 credits as of 2026-10-28. APIs.io lists 3 pricing plans for NeverBounce, with each plan's price, limits and inclusions under Pricing on this page.

Does NeverBounce have an MCP server?

Yes. APIs.io lists 1 MCP server for NeverBounce: Remote MCP server at developers.neverbounce.com.

Is the NeverBounce API ready for AI agents?

NeverBounce has a Kin Score of 65.7 out of 100 (strong) and an Agent Readiness score of 44.7 (agent-ready), scored by API Evangelist on 2026-11-06.

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