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.
Solid contracts, transparent operations, and an easy start — typically complete on four or five facets with one clear soft spot.
API Evangelist profiles NeverBounce the way a machine reads it — 17 machine-readable artifacts across 1 API, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — NeverBounce scores 59.2/100 (strong), with a separate agent-readiness read of 36/100 (agent ready). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance. Every facet and dimension name is a link: it opens that measurement's page on APIs.io, where the rating runs across the whole catalog — the exact checks that feed it, how every profiled provider distributes on it, and who is at the top of it.
Kin Score
How this is scored →scored 2026-09-08 · rubric v0.20.0
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title="NeverBounce on API Evangelist — API profile and Kin Score">
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How we profile NeverBounce
Each block below is one kind of artifact we hold for NeverBounce. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 5
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
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 collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.
Open, tool-agnostic API collections (OpenAPI-derived and Bruno).
API Collection
OPEN COLLECTIONNeverBounce API v4 Account API
OPEN COLLECTIONNeverBounce API v4 Account Jobs API
OPEN COLLECTIONNeverBounce API v4 Account Single API
OPEN COLLECTIONNeverBounce API v4
OPEN COLLECTIONMCP Servers 1
Model Context Protocol servers expose these APIs directly to AI agents. We profile them because agent-native access is the fastest-growing way this provider's capabilities actually get used.
Model Context Protocol servers that expose these APIs to AI agents.
NeverBounce Developer Docs MCP
MCP SERVERPricing Plans 1
Pricing is part of the interface. Machine-readable plans tell you what a tier costs and includes before you commit — one of the things the Kin Score reads for access clarity — renamed from commercial clarity in rubric 0.12, because a free statutory interface has access terms and no commercial ones.
Published pricing tiers and plan structures.
Rate Limits 1
Rate limits are the difference between a demo that works and a production integration that doesn't fall over. Publishing them is an operational-transparency signal — and a hard requirement for any agent that plans its own throughput.
Documented rate limits and quota policies.
Neverbounce Rate Limits
RATE LIMITSEvent Specifications 1
Not every API is request/response. AsyncAPI describes the event-driven and streaming side — the webhooks and channels — so the asynchronous half of the interface is documented the same way the synchronous half is.
AsyncAPI definitions for this provider's event-driven and streaming APIs.
Neverbounce Webhooks
ASYNCAPISecurity Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Agentic Access 1
An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.
Recommended x-agentic-access execution contracts for AI agents.
Resources
Every other property we hold for NeverBounce — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Get Started 3
Portal, sign-up, and the first successful call
Documentation 2
Reference material describing how the API behaves
Agent Surfaces 5
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 7
Pagination, idempotency, versioning, errors, and events
Scroll within the panel for all 7 ·
Build 5
SDKs, sample code, and the tooling you integrate with
Access & Security 2
Authentication, authorization, and security posture
Operate 5
Status, limits, changes, and where to get help
Commercial 4
Pricing, plans, and the legal terms of use
Company 3
The organization behind the API
← All providers · Data indexed from github.com/api-evangelist/neverbounce · machine-readable index on apis.io
This is an independent, third-party profile of NeverBounce, published by API Evangelist. We do not operate, host, resell, or support these APIs, and we are not affiliated with or endorsed by the company unless stated above. Everything here is built from publicly available information — the company's own site, developer portal, documentation, public repositories, and the specifications it publishes for public use. Nothing is obtained by breaching a system, defeating an access control, or using credentials.
The Kin Score and Agent Readiness rating are independently calculated assessments of a company's public API artifacts, scored against a published rubric. They are not certifications, endorsements, security assessments, or audits.
Corrections, re-scores, and removal are free — no partnership or purchase required, and you do not need to justify the request. A removed company is recorded as unrated, never scored zero for having asked. Acknowledgement within one business day; removal within two.
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