Free online developer tools
Format a payload, decode a token, check a subnet or read a log line. 306 focused tools in 41 categories, without an account and without installing anything.
The everyday tools most developers reach for: formatters, decoders, converters and calculators.
Format JSON with exact numbers while keeping large IDs and decimals intact
Decode JWT claims as UTC dates and verify signatures with explicit keys
Convert between Unix timestamps and dates across units and timezones
Test JavaScript regex with visible captures and group replacements
Convert between text and Base64 with strict UTF-8 and alphabet options
Design five-field cron schedules with timezone context and run previews
Determine network boundaries and host counts with CIDR and netmask support
Generate UUIDs v1, v3, v4, v5, v6 and v7 or create repeatable names
Eight topic groups, each split into focused categories. Open a category to see every tool for that format or job.
Format, validate, convert and query structured data: JSON, YAML, TOML, XML, CSV, schemas and binary files.
Clean up and compare text, test regular expressions, encode or escape strings, inspect Unicode and generate IDs.
Convert timestamps and time zones, build cron schedules, and work with number bases, bits and units.
Debug HTTP requests and APIs, parse URLs, decode JWTs, build security headers and generate hashes and keys.
Look up DNS records, calculate subnets, inspect TLS certificates and check email authentication records.
Work with SQL and databases, Git, package versions, Linux, Docker, Kubernetes, cloud resources, CI/CD and logs.
Format HTML and CSS, generate CSS effects, check color contrast, test SEO files and debug iOS and Android config.
Decode binary protocols and serialization formats, inspect LLM and MCP payloads, and look up developer references.
Real tasks rarely stop at one tool. These are common chains you can follow from start to finish.
Turn a copied cURL command into a request, send it, decode the bearer token and read the JSON response.
Convert a spreadsheet export to JSON, check the structure, then generate TypeScript types for it.
Filter the logs around the incident, clean up the stack trace and map minified frames back to source.
Look up the current DNS records, build SPF and DMARC policies, then verify the published result.
Small utilities should be quick to open and clear about what happens to your data.
Most tools, from the JSON formatter to the JWT debugger, process input with JavaScript in your browser. A few tools need the network to do their job, such as DNS lookup, the SSL checker, the redirect checker and the webhook tester. They run only when you start them and say on the page what they send.
Each tool does one job and opens ready to use, with an example you can load in one click. There is no account, no workspace to configure and nothing to install. Bookmark the pages you need and they stay the same URL.
What people usually want to know before pasting real data into a new site.
Yes. Every tool is free to use without an account or credit card. Tools that call an external service, such as DNS lookup or the SSL checker, have rate limits to keep that service available.
Not for most tools: formatters, converters, decoders and calculators run in your browser. Network tools like DNS lookup, the HTTP header checker, the redirect checker, the webhook tester and the SSL checker send only what they need after you start them, and each page explains the request.
No. HeyUtils has no user accounts. Open a tool page and use it right away.
There are 306 tools in 41 categories, covering data formats, text and encoding, time, APIs and security, networking, DevOps, frontend and mobile, and protocols. The full list is on the all tools page.
Yes. Use the feedback link on any page to describe the task you are trying to do. Requests that come up often are the first ones we add.
Didn't find your answer?
Browse all 306 tools by category, or press the search shortcut on any page to jump straight to one.
No account. No install. Most tools run entirely in your browser.