Free developer tools
Small tools for people who run things on a schedule.
Cron, uptime, SSL, regex, curl, and OpenAPI utilities — all in one place. No login. The AI tools redact secrets in your browser before anything ships to the model.
What's in the box
Nine focused utilities.
- Each tool answers one specific question. SSL expiry, domain expiry, SLA downtime, cron syntax, regex, curl semantics, OpenAPI monitoring shape.
- AI inputs are scrubbed for secrets in the browser before any request leaves your machine. You see the redacted payload before you submit.
- Every result that can become a schedule gets a one-click deep link into Crontap with URL, method, headers, body, cron and timezone pre-filled.
Cron & uptime utilities
The fundamentals.
Three browser-and-server utilities for the questions developers answer most often: does this cert expire soon? when does this domain renew? how much downtime does my SLA permit?
SSL expiry checker
Check when any HTTPS certificate expires. Get the issuer, validity window, and a Crontap deep link to keep watching it.
Domain expiry checker
RDAP + WHOIS fallback. See when a domain expires, who registered it, and set a Crontap reminder.
SLA uptime calculator
Convert SLA percentages to allowed downtime per day, week, month, quarter, and year. With nines breakdown.
AI tools
Powered by AI intelligence.
Six AI-powered tools with JSON-mode structured output and a client-side secret scrubber. Each one is one click away from a pre-filled Crontap schedule.
Cron from English
AIDescribe what you want in plain English. Get a cron expression, explanation, next-run timestamps, and a deep link.
Cron debug
AIPaste a broken cron line. AI explains what went wrong and suggests fixes. Secrets are scrubbed client-side first.
Cron migrator
AIMove from Vercel Cron, GitHub Actions, AWS EventBridge, Heroku, GCP, or raw crontab into Crontap with one click per schedule.
Regex from English
AIAI regex generator. Four flavors (JS, Python, PCRE, Go). Test cases included. Use it as a Crontap response check.
Curl explainer
AIPaste any curl, get a plain-English breakdown of every flag, header, and body. One click to schedule it in Crontap.
OpenAPI monitoring planner
AIUpload an OpenAPI spec, get the top 10 endpoints worth monitoring with suggested cadences and per-row Crontap deep links.
FAQ
Common questions
- Are the Crontap tools really free?
- Yes. Every tool listed here runs in your browser or through Crontap's backend at no cost, with no signup. The AI tools are powered by Gemini and we cap usage to keep things free at common volumes.
- Do you send my secrets, headers, or API keys to an AI?
- No. The AI tools that accept potentially-sensitive input (cron debug, cron migrator, curl explainer) run a client-side secret scrubber before anything is submitted. Bearer tokens, JWTs, API keys, AWS keys, GitHub PATs, OpenAI keys, Stripe keys, Google API keys, Slack tokens, generic api-key/password headers, and URL-embedded passwords are replaced with [REDACTED] placeholders. You see a preview of exactly what gets sent before submitting.
- Why is there a 'Schedule in Crontap' button on every tool?
- The tools are designed to feed into Crontap's scheduler. If you just used the curl explainer to understand a request, the next natural step is to run it on a schedule. The deep links pre-fill the new-schedule form with URL, method, headers, body, cron expression, and timezone so you don't have to retype anything.
- Can I rely on these tools for production monitoring?
- The tools are informational. The SSL checker, domain checker, and SLA calculator are accurate point-in-time queries. For ongoing monitoring ("alert me when this changes"), set up an actual Crontap schedule, which is what each tool's CTA links to.
- Are these tools open-source?
- They're part of the Crontap website codebase. The shared infrastructure (secret scrubber, Gemini client, schedule deep-link builder) lives at lib/tools/ in the repo. Issue reports and PRs are welcome.
Ready to fix it?
Point Crontap at any URL. Pick any cron. Done.
WordPress, Shopify, Railway, Cloud Run, Vercel, HubSpot, Ghost, your own box. If it answers HTTP, Crontap can drive it on a clock you can read, in the timezone that actually matters, and page you when something breaks.
Free forever tier ・ No credit card required
/wp-cron.php?doing_wp_cron=1
Schedule
"every 5 minutes"
Next
in 23s