API Reference · v1

Email Verification API

Verify single emails, run bulk jobs, find professional emails by name, embed the FoxGuard widget on any form, and manage your API keys and credits — all on the same nine-check engine behind every call.

Base URLapi.verifox.ai/v1AuthX-API-Key headerRate limit60 req/minFormatJSON over HTTPSLatency~380ms

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Overview

What does the Verifox API actually do?

One nine-check engine, three ways to call it, and a verdict you can bill against.

What does each call check?

Every call runs the same nine-check engine behind our email verification service: RFC syntax, domain & MX, SMTP handshake with mailbox ping, disposable detection, role detection, catch-all detection with AI-confidence scoring, domain age, and SPF/DKIM/DMARC authentication. That last mile matters: 20–40% of B2B lists fail at catch-alls, and confidence scoring keeps those addresses instead of discarding them as unknown. Accuracy sits at 99.99%.

How do I integrate it?

Integrate three ways: REST endpoints handle real-time checks (~380ms median, sub-50ms cached) and bulk jobs at ~10,000/minute. The Email Finder module turns name + domain into a verified address. For agentic stacks, the MCP server exposes the engine as native tool calls. One balance covers everything: single checks, bulk uploads, finder results, and the FoxGuard widget.

What happens behind every API call?

Every call (single verify, bulk job, finder, or widget) runs the same nine-check engine and returns one tagged verdict you can act on.

01REQUEST

Call the endpoint

Send any address with your key in the X-API-Key header. Bulk jobs take a whole CSV instead.

GET /v1/email-validation/:email

02ENGINE

Nine checks per address

Catch-all domains come back with a 0 to 100 AI confidence score instead of an unknown.

Syntax, domain, MX, SMTP, disposable, role, catch-all, domain age, authentication

03RESPONSE200 OK

Read the JSON verdict

Branch on status, and on confidence for catch-alls. The full breakdown ships in the same object.

validriskyinvalid

Median ~380ms, sub-50ms when cached

Quickstart

Your first verify in under a minute

01
Create an API key
Sign up and mint a key in the dashboard. 1,000 free credits on signup, 2,500 with a work email, no card.
02
Call the endpoint
Pass any address to GET /v1/email-validation/:email with your key in the header.
03
Read the verdict
isValid, reachable, and the full nine-check breakdown come back in one JSON object.

1curl -X GET "https://api.verifox.ai/v1/email-validation/[email protected]" \2  -H "X-API-Key: vfx_your_api_key"

200 - OK

1{2  "email": "[email protected]",3  "domain": "example.com",4  "isValid": true,5  "reachable": "safe",6  "syntax": true,7  "smtp": {8    "deliverable": true,9    "catchAll": false,10    "hostExists": true11  },12  "isFree": false,13  "isRole": false,14  "isDisposable": false,15  "hasGravatar": true,16  "suggestion": null,17  "verifiedAt": "2026-03-31T10:30:00Z"18}

5 modules · 22 endpoints

Browse the API

Five modules cover the whole pipeline: validate what you have, find what you don't, guard your forms, and meter it all with keys and credits.

Email Validation

Verify individual emails or run bulk jobs. Checks syntax, SMTP deliverability, disposable providers, role accounts, and more.

GET/:email//bulk5 endpointsReference

Email Finder

Find anyone's professional email address using their name and company domain. Uses smart permutation and SMTP verification.

/GET/:jobIdGET/history5 endpointsReference

FoxGuard Widget

Drop-in real-time email validation for any HTML form. Add two script tags before </head> — FoxGuard auto-discovers every [type="email"] input and validates as the user types. No backend changes. Supports a free public tier (4 req/day) and unlimited with an API key.

GET/validate/public-verify2 endpointsReference

API Keys

Create and manage API keys for authenticating requests. Each key has a scope, optional IP restrictions, and an expiry. The full key is shown only once on creation — store it securely.

/GET/GET/analytics4 endpointsReference

Credits & Balance

Check your Fox Credits balance, view the transaction history for every deduction and top-up, and pull usage statistics for dashboard charts.

GET/balanceGET/transactionsGET/stats3 endpointsReference

MCP Server

The same engine exposed as native tool calls for Claude, Cursor, and your own agents.

verify_emailfind_emailget_credits3 toolsAgent guide

Authentication

One header, four scopes

All REST endpoints require an API key via the X-API-Key header. Create keys in your dashboard and scope each one to exactly what it needs.

Key scopes

fullAll endpoints

verifyEmail verification only

listsList management only

read-onlyGET requests only

No key? Use FoxGuard

The widget's free public tier verifies 4 emails per day per device with one script tag, no API key at all.

Widget docs Try it live

Error codes

Every status, one shape

All errors return { error: string } with the HTTP status telling you what to do next.

Code	Name	Meaning
200	OK	Request completed
201	Created	Resource created
202	Accepted	Job started. Poll for results
400	Bad Request	Check your request parameters
401	Unauthorized	Invalid or missing API key
402	Payment Required	Insufficient Fox Credits
404	Not Found	Resource doesn't exist
429	Rate Limited	Slow down and retry after the window resets
500	Server Error	Retry after a short delay
503	Unavailable	Database unavailable. Retry shortly