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Comprehensive analysis across 20+ metrics with AI-generated code fixes — powered by Code Surgeon
Subto.One helps developers and teams quickly identify performance, SEO, accessibility and security issues on public websites and provides actionable recommendations and automated patches to improve reliability and user experience.
100% Free Forever • Up to 10 Scans/Day • No Credit Card Required
You've used all your free scans for today
Free visitors get 3 scans per day. Sign in with Google for 10 scans/day, Full mode, and API access — still free.
Get actionable insights in three steps
Enter a URL
Paste any public website URL. Our engine loads the page in a real browser, capturing every request, script, and interaction.
AI Analysis
We analyze 20+ metrics across performance, accessibility, SEO, and security — then our AI identifies root causes and generates precise fixes.
Get Fixes
Review AI-generated patches, apply them with confidence, and track improvements over time. Export results or share with your team.
Everything you need to ship better websites
Performance Audits
Lighthouse scores, Core Web Vitals, waterfall charts, and bundle analysis
SEO Intelligence
Meta analysis, heading structure, link audits, image optimization, and schema validation
Security Scanning
CSP, CORS, cookie flags, HSTS, exposed files, and dependency vulnerability checks
Accessibility Testing
WCAG compliance checks, contrast analysis, ARIA validation, and screen reader compatibility
JS Dependency Graph
Interactive runtime execution maps showing module dependencies and interaction paths
AI Code Surgeon
Upload your codebase and get targeted patches for every issue — review before you apply
Frequently asked questions
Is Subto.One really free?
Yes. Free users get 3 scans per day. Sign in with Google for 10 scans per day, Full scan mode, and API access — all still free. No credit card required, ever.
What does a scan actually check?
Each scan evaluates 20+ metrics including Core Web Vitals (LCP, INP, CLS), Lighthouse scores, SEO metadata, heading structure, link integrity, security headers, CSP configuration, CORS policies, cookie security, accessibility compliance, JavaScript dependencies, and runtime behavior. Full mode adds interaction testing and session recording.
How does the AI Code Surgeon work?
Upload your codebase (JS, TS, CSS, HTML, JSON, and more) and our AI analyzes the full dependency graph. It identifies issues, explains why they matter, and generates precise unified-diff patches that follow your existing code style. You review every change before applying — nothing is automatic.
Do you store my website data?
Scan results are stored temporarily for your reference. Uploaded code files for the AI Code Surgeon are processed in-memory and discarded after analysis. We do not sell, share, or train on your data. See our Privacy Policy for details.
Can I use Subto.One in my CI/CD pipeline?
Yes. Our public API supports programmatic scans with API key authentication. You can integrate it into GitHub Actions, GitLab CI, or any pipeline that can make HTTP requests. See the API documentation for rate limits and endpoint details.
What's the difference between Basic and Full scan modes?
Basic mode skips the heaviest interaction testing and session recording for speed, completing in 5-10 seconds. Full mode runs comprehensive interaction tests, records a session video, and provides deeper runtime analysis — typically 15-30 seconds.
API Documentation
Integrate Subto.One's powerful analysis engine into your applications
Your API Key
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API keys may rotate frequently. If your key changes, update your code and environment configuration right away.
Account Usage
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These counters are increment-only and reflect totals even after individual scans expire.
Rate Limits
API Reference (Public)
Overview
Public endpoints available to API key holders.
- POST /api/v1/scan — start a scan
- GET /api/v1/scan/:scanId — retrieve scan results
- GET /api/v1/health — health check (no auth required)
Authentication
Include your API key in the request header:
X-API-Key: sk-your-api-keyOr use the Authorization header:
Authorization: Bearer sk-your-api-keyRate Limits
API keys are rate-limited to 1 request per minute. Responses include X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset. On limit exceeded the API returns HTTP 429 and a Retry-After header.
Examples
cURL
curl -X POST https://subto.one/api/v1/scan \
-H "X-API-Key: sk-your-api-key" \
-H "Content-Type: application/json" \
-d '{"url": "https://subto.one"}'JavaScript
fetch('https://subto.one/api/v1/scan', {
method: 'POST',
headers: {
'X-API-Key': 'sk-your-api-key',
'Content-Type': 'application/json'
},
body: JSON.stringify({ url: 'https://Subto.One' })
}).then(r => r.json()).then(console.log);Errors
Generic error responses: 400 Bad Request, 401 Unauthorized, 429 Too Many Requests, 500 Internal Server Error.
Use the Subto.One CLI for scans directly from your terminal.
Teams
Work together on website analysis. Share scans, discuss issues, and approve changes as a team.
No Team Yet
Create a team or join an existing one to collaborate
My Team
0 membersMembers
Recent Scans
No scans yet
Shared Dashboard
All team members see the same scan results - no duplicate work
Team Discussions
Comment on issues, tag teammates, and discuss fixes collaboratively
Approval Workflows
Request reviews and get team sign-off before deploying changes
Role-Based Access
Control who can view, edit, or approve with Owner/Admin/Viewer roles
Project Organization
Group scans by client or project and track historical performance
Easy Invites
Invite teammates by email or share a simple 6-character code
Sign in to access Teams
Create and join teams to collaborate with your colleagues
System Analysis
Core Web Vitals
Runtime Interaction Graph
Issues by Impact
SEO Intelligence
Meta Analysis
Heading Structure
Link Analysis
Image Analysis
Code Surface Explorer
Comprehensive Interaction Testing
Ask AI About This Code
Did we not get everything? Upload your files below to get help.
Code Surgeon
.js, .ts, .css, .html, .json, .env, .md, .zip