Developer Documentation

This is your technical guide. If you want to learn how it works, visit the Workflow library. If you're ready to build, you're in the right place.

Sample Output

See real JSON responses before you build.

Quickstart

Headers, paths, and your first 200 OK.

DKIM Selectors

How to find and use DKIM selectors.

Scoring Engine

How we calculate risk based on official rules.

Route by Workflow Intent

Auditing multiple clients?

Read the MSP Onboarding Workflow or the Bulk Domains guide.

Verifying SaaS signups?

Read the Sender Verification Workflow.

Proving a fix worked?

Read the Comparison Workflow or the Compare guide.

Need an OpenAPI spec?

View the API Reference or download openapi.json.

Open Source & Tooling

Prose Tokenizer

Deterministic English prose and Markdown segmentation library. Built for writing analysis and AI pipelines.

Concept Guides

DMARC p=none Risk

Why monitoring mode is not enforcement, and how to move toward quarantine or reject.

SPF Lookup Limit

How recursive includes can break SPF at the 10-lookup ceiling.

DKIM Discovery

How selector discovery works and why explicit selectors improve audit confidence.

Free Record Tools & API Audit Pages

MX Record Checker

Read live MX records over DNS — priority order, duplicate priorities, null-MX detection.

Email Header Analyzer

Paste raw headers for the hop-by-hop Received trace plus SPF, DKIM, and DMARC verdicts.

TLS-RPT Record Generator

Publish a TLS-RPT record so senders report inbound TLS failures to you.

Email Domain Security Audit API

Scored audits of how SPF, DKIM, and DMARC work together, in plain language.

BIMI Audit API

Audit your BIMI record, logo SVG hosting, and DMARC enforcement readiness.

MTA-STS & TLS-RPT Audit API

Audit MTA-STS policy, TLS-RPT reporting, and transport security health.

Core Endpoints

Free Domain Audit

Fast score, grade, risk, and top findings without using your paid credits.

Pro Domain Audit

Full findings, technical proof, score breakdown, and provider-aware recommendations.

Bulk Domain Audits

Check and sort up to 50 domains in a single request.

Compare Two Checks

Compare two checks of the same domain to see your progress.

Remediation Fix Plan

Turn security findings into clear, ready-to-use fix steps.

Create Pro Reports

Create professional HTML or data reports from your audit results.