Usability62Design57Speed88Security64Accessibility80Growth58

Cycling through all six. Tap any point to stop.

Measured on six things

MCP email verification for AI agents

Design

57

The homepage reads as raw developer documentation rather than a product landing page. No visual hierarchy, no accent color on the main heading, code blocks without syntax highlighting or copy buttons, and dense unbroken text below the fold. Functional but visually flat.

Screenshots

1 / 1

About this app

uChecker is honest email verification with an MCP endpoint for agent workflows. Agents check contacts before outreach. Docs at https://uchecker.net/en/mcp. Returns Good, Bad, or Unknown. Includes free SPF, DKIM, and DMARC checkers. Honest validation for agents, not generative AI.

Key features

  • 1MCP server endpoint for AI agent workflows (Claude Code, Cursor, VS Code) with tools for validation, task tracking, and export
  • 2SMTP-based email verification returning good/bad with reasons: mailbox_not_found, domain_not_found, smtp_rejected, disposable, role-based, catch-all
  • 3Bulk validation up to 10,000 emails per call, REST API with interactive docs, no rate limits, 1 credit per email

Target customer profile

Drawn from the product itself, not from a survey.

Demographic

Sales and CRM Managers at B2B companies

Pain points

Wasting time on leads with invalid emails; poor data quality in CRM; lost productivity from manual verification.

Primary needs

Automated email validation integrated with AI tools; high accuracy; easy integration with existing systems.

Demographic

Developers and IT teams building AI-powered applications

Pain points

Difficulty integrating email validation into MCP-compatible AI agents; need for a reliable API without extensive coding; concerns about email deliverability and avoiding blacklists.

Primary needs

Simple MCP server setup; comprehensive validation tools; programmatic access via API.

Demographic

Digital Marketers and Campaign Managers

Pain points

High bounce rates damaging sender reputation; low campaign ROI due to fake or disposable emails; need to clean large lists efficiently.

Primary needs

Bulk email validation; disposable and role-based address detection; deliverability analytics.

Scout Review

Written by AI from measured evidence, scored out of 100.

uChecker is an email verification API with an MCP endpoint aimed at AI agent workflows. It does the core job well: SMTP verification, MX checks, disposable and role-based detection, bulk validation up to 10,000 per call, and a REST API with interactive docs. The MCP integration is the differentiator — agents can call validate_email, wait_for_task, and export_results without REST boilerplate. Pricing is straightforward at 1 credit per email, with syntax-invalid addresses free and no rate limits. The site is fast (96 mobile Lighthouse) and accessible (100 a11y score), but the homepage design is flat and documentation-like, and security headers are incomplete. Against NeverBounce, ZeroBounce, and Hunter.io, uChecker competes on MCP-native integration rather than verification accuracy or scale. It is a competent, focused tool for a specific emerging use case.

Measure by measure

Usability

62

Docs are solid: quick-start curl examples, two auth methods, task lifecycle states, and a clear result breakdown. But the homepage has no 'Get started' CTA above the fold and setup assumes you already have an API key and MCP client — new users get no hand-holding.

Design

57

The homepage reads as raw developer documentation rather than a product landing page. No visual hierarchy, no accent color on the main heading, code blocks without syntax highlighting or copy buttons, and dense unbroken text below the fold. Functional but visually flat.

Speed

88

Lighthouse mobile performance 96/100 with LCP 2.3s, CLS 0, TBT 153ms, FCP 939ms. Desktop scores 87/100. The site is fast and stable — no layout shift, quick first paint, and no user complaints about lag in the collected evidence.

Security

64

HTTPS enforced with HSTS, X-Content-Type-Options and Referrer-Policy present, SPF and DMARC verified — 8/12 checklist points. Missing CSP, frame protection, and Permissions-Policy. API key auth with manual reset and documented JWT lifetimes. No SOC 2 or audit claims found.

Accessibility

80

Lighthouse accessibility audit scores a perfect 100/100. The site is keyboard-navigable and contrast appears solid. However, there is no published accessibility statement or WCAG mention, and the site is English-only with no multi-language support observed.

Growth

58

A real problem — LLMs invent plausible-looking emails — with a specific wedge: MCP-native validation for agent workflows. The category is emerging and few competitors offer dedicated MCP endpoints. But the core verification tech is commoditized and the target segment is narrow.

Improvement areas

  • Homepage design: add visual hierarchy, accent color, syntax highlighting, copy buttons, and a prominent CTA above the fold
  • Security headers: implement CSP, frame protection, and Permissions-Policy to reach 11/12 checklist points
  • Accessibility and internationalization: publish an a11y statement and add multi-language support beyond the /en/ path

Design & Usability

uChecker's homepage is a developer's README rendered as a web page. The visual audit found no hierarchy, no accent color on the main heading, and code blocks without syntax highlighting or copy buttons. It works, but it does not sell. The usability story is stronger: the docs page delivers quick-start curl examples, two authentication methods (API key and JWT), a clear task lifecycle, and a result breakdown that explains why 'catch-all' and 'role-based' deserve different treatment. The gap is onboarding — the homepage assumes you already have an API key and an MCP client configured. There is no 'Get started' CTA above the fold, no interactive demo, and no guided path from curious visitor to first validation call. For a developer tool, that is a missed conversion opportunity, not a fatal flaw. The docs themselves are genuinely good: concise, example-driven, and honest about SMTP limitations like greylisting and rate limits on the receiving side.

Speed & Security

Speed is uChecker's strongest measured dimension. Lighthouse mobile performance scores 96/100 with an LCP of 2.3s, CLS of 0, TBT of 153ms, and FCP of 939ms. Desktop scores 87/100. The site is lightweight, stable, and snappy — no layout shift, no user complaints about lag. Security is competent but incomplete: HTTPS is enforced with HSTS, X-Content-Type-Options and Referrer-Policy are present, and SPF and DMARC records are verified, totaling 8/12 checklist points. Missing are CSP, frame protection, and Permissions-Policy — the headers that mitigate clickjacking and injection attacks. Authentication is well-documented: API keys that never expire until manually reset, plus JWT bearer tokens with 1-hour access and 7-day refresh lifetimes. There is no SOC 2 report, no ISO certification, and no bug bounty program mentioned. For an early-stage API product handling email lists, that is normal but worth watching as the customer base grows.

Accessibility & Growth

Accessibility scores a perfect 100/100 on the Lighthouse audit, which covers automated checks but not the full WCAG surface. The site is keyboard-navigable and contrast appears solid. What is missing: a published accessibility statement, any WCAG conformance claim, and multi-language support — the site is English-only despite the /en/ path suggesting internationalization was planned. Growth potential is the most interesting dimension. uChecker names a real problem — language models cannot distinguish john@exampel.com from john@example.com — and offers a specific wedge: an MCP-native endpoint that lets agents validate contacts before outreach. The category is emerging, and few competitors in the alternatives list (NeverBounce, ZeroBounce, Hunter.io) offer dedicated MCP servers. But the core verification technology is commoditized, and the target segment — developers building MCP-compatible agents — is narrow. The domain was registered in April 2025, so the product is early. The idea has room to grow if MCP adoption accelerates, but the moat is thin.

Conclusion

uChecker is not trying to be everything to everyone. It is a focused email verification API that bets on MCP becoming the standard way agents call tools. That bet might pay off — the MCP ecosystem is growing, and dedicated email-validation MCP servers are rare. The execution is solid where it counts: fast site, clean docs, honest result semantics (good/bad, no maybe), and transparent pricing. Where it falls short is presentation and hardening: the homepage does not sell the product, security headers are incomplete, and there is no accessibility statement or multi-language support. For developers already building MCP-compatible agents, uChecker is worth a look. For everyone else, it is a competent API in a crowded category with a thin differentiator.

Suggestions for improvement

  • Add a prominent 'Get started' CTA and a 3-step onboarding flow above the fold on the homepage.
  • Add syntax highlighting and copy buttons to code blocks; break up long text blocks with subheadings.
  • Implement CSP, frame protection, and Permissions-Policy headers to reach 11/12 security checklist points.
  • Publish an accessibility statement and consider multi-language support given the /en/ URL structure.
How we score

Alternatives comparison

Named competitors, point by point. Nobody paid to appear here or to be left out.

uCheckerNeverBounceZeroBounceHunter.io
MCP server for AI agent integrationYes — native MCP endpoint with 10 tools for validation, task tracking, and exportNo — REST API only, no MCP serverNo — REST API only, though MCP integration is possible via custom wrapperNo — REST API only, focused on email finding and verification
Bulk email validationUp to 10,000 emails per call via validate_emails toolYes — bulk validation via API and dashboard uploadYes — bulk validation with list cleaningYes — bulk verification available on paid plans
Free tier / trialSyntax-invalid addresses free; credits-based pricing, no explicit free tier mentionedFree trial with limited credits100 free credits on signupFree plan with 25 searches/month
Result semanticsGood or Bad only — no 'maybe'; reasons include mailbox_not_found, smtp_rejected, disposable, role-basedValid, Invalid, Catchall, Unknown, DisposableValid, Invalid, Catch-all, Unknown, Spamtrap, Abuse, Do_not_mailValid, Invalid, Accept-all, Unknown
Authentication methodsAPI key (x-api-key header) and JWT bearer tokens (1h access, 7d refresh)API keyAPI keyAPI key

Comparing options? See uChecker alternatives, scored side by side

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