Free tools
Free tools for developers
Every Stripe test card number: brands, countries, declines, 3D Secure, disputes, fraud and ACH, with copy buttons.
Token counter →Count GPT tokens exactly and estimate Claude and Gemini tokens, then see what the prompt costs on each model.
Cron expression generator →Build a cron schedule, read any crontab line in plain English and see its next run times.
Chmod calculator →Tick read, write and execute boxes and get the octal (755) and symbolic (rwxr-xr-x) permissions and the command.
More free calculators and lists
- Stripe fee calculator · The fee on any payment and what to charge to pass it on.
- Hosting cost calculator · Your traffic priced on Vercel, Netlify, Cloudflare and more.
- Email pricing calculator · Resend, Postmark, SES, Mailchimp, Kit and more for your volume.
- AI model pricing · Price per 1M tokens across 50+ models, with a monthly calculator.
- Free APIs · APIs with a real free tier: limits, auth and the catch.
- Is it down? · Live status of GitHub, OpenAI, Vercel, Stripe and 60+ dev tools.
Looking for a tool to build with instead? Browse every dev tool on DevHunt or free alternatives to paid dev tools.
FAQ
Are these tools free?+
Yes, with no sign-up and no limits. They run in your browser, so what you type (a prompt, a cron line, a card number) isn’t sent to DevHunt or anyone else.
Can I link to a result?+
The cron generator, chmod calculator and Stripe fee calculator keep your input in the page URL, so copying the link shares the same result.
Where do the numbers come from?+
From official sources, with the date they were checked on each page: Stripe’s testing docs and pricing page for the Stripe tools, each provider’s pricing page for the token costs.