Developer Tools

What you can do with Developer Tools

• Test and generate regex patterns, validate a pattern against sample input with the Regex Tester, or build one from examples with the Regex Generator from Text.
• Translate curl commands into code, convert a curl call to fetch, Python requests, or PHP cURL without rewriting flags by hand.
• Schedule cron jobs, build expressions with the Crontab Generator and preview the next runs with the Cron Parser.

Pick Developer Tools when the input is code, a config fragment, or a regex pattern and the output is another piece of code or a live verification. For byte-level encoding (base64, URL encoding, hashing), the right category is Encoding Tools. For JSON, CSV, XML, or YAML reshaping, flatten, diff, or infer a schema, Data Tools operates at the document level. Character-level text work like case changes and slug conversion sits in Text Tools.

The Developer Tools toolkit

Tool	What it does	When to use
Regex Tester	Matches a regex against test strings with live highlighting	Debugging a pattern before committing it to production
Regex Generator from Text	Infers a regex from input/output examples	Extracting order IDs or dates from a log sample
Regex Generator	Builds common regex patterns from a checklist	Matching emails, URLs, IPs, or phone numbers quickly
Regex Cheat Sheet	Reference card for syntax, quantifiers, and lookarounds	Looking up b vs B mid-review
Crontab Generator	Builds a cron expression from plain-English intervals	Scheduling a 2 a.m. weekly backup job
Cron Parser	Lists the next N firing times for a cron expression	Verifying 30 */4 * * 1-5 before deploying it
curl to fetch	Converts a curl command to a JavaScript fetch call	Porting an API debugging session from Postman to a web app
curl to Python requests	Converts a curl command to a requests call	Turning a one-liner test into a Python script
curl to PHP cURL	Converts a curl command to PHP curl_* calls	Adding a remote API call to a legacy WordPress plugin
Docker Compose Generator	Scaffolds a docker-compose.yml from service fields	Standing up a Postgres + Redis + app stack on a new laptop
Diff Checker	Compares two blocks of text and highlights changes	Reviewing a config drift between staging and production
JavaScript Minifier	Strips whitespace and renames locals in JS	Shrinking a 40 KB script before pasting it into a CMS
HTML to Markdown	Converts HTML into CommonMark Markdown	Importing a scraped blog post into a Jekyll or Hugo site
IP Subnet Calculator	Computes network, broadcast, and host range from a CIDR	Planning a /24 split for a new VPC

Regex utilities cover writing, testing, and debugging patterns. The Regex Cheat Sheet is for syntax lookup, the Regex Generator from Text infers a pattern from input/output examples, and the Regex Tester confirms the match before you paste it into code.

Scheduling and HTTP translators solve the same small-text-must-be-exact problem. The Crontab Generator writes the expression; the Cron Parser reads it back with the next five runs. The three curl converters, to fetch, to Python requests, and to PHP cURL, port a call into another language without rewriting flags by hand.

Format and code converters round out the set. The Docker Compose Generator scaffolds a multi-service stack, the Diff Checker highlights line-level changes, the JavaScript Minifier strips a file for deployment, HTML to Markdown flattens HTML into CommonMark, and the IP Subnet Calculator turns a CIDR into network, broadcast, and host-range values.

How to choose the right Developer Tool

• If you're debugging an existing pattern that needs to match 20 sample strings → Regex Tester.
• If you need a cron expression for an off-hours backup → build it in the Crontab Generator and verify with the Cron Parser.
• If you captured a request with curl -H ... -d ... and want it in a Python test → curl to Python requests.
• If you're planning a VPC split from a CIDR → IP Subnet Calculator.
• If you're comparing two config files line-by-line without opening git → Diff Checker.

The trade-off that matters is convenience vs. reproducibility. Browser tools are faster for one-offs, test a regex, generate a cron expression, or convert a curl call in 30 seconds. For anything that ends up in CI, wire the equivalent logic into your repo: pytest fixtures for regex tests, a checked-in docker-compose.yml, a crontab under version control. The tools here are the scratch pad, your codebase is the source of truth.

Frequently asked questions

Are these developer tools free to use?

Yes. Every tool runs free in your browser with no account, no rate limit, and no paid tier. Computation happens client-side, so a private curl command or an internal regex stays off our servers. The full set is 39 utilities across regex, cron, curl, Docker Compose, and network math.

Do my inputs leave the browser?

No. Every tool in this category is client-side JavaScript, the regex engine, the curl parser, the cron clock, and the diff algorithm run in your tab. That matters when you paste a production connection string into the Diff Checker or an API token into curl to fetch. Nothing is logged and nothing is posted to a server.

Which regex flavor does the Regex Tester use?

The Regex Tester runs JavaScript's built-in RegExp engine, ECMAScript flavor. That covers the standard metacharacters, character classes, quantifiers, alternation, groups, lookaheads, and named groups ((?<name>...)). For PCRE-only features like recursive patterns and conditional groups, reach for a PCRE-specific tester.

What cron syntax does the Crontab Generator support?

The Crontab Generator produces standard 5-field Unix cron expressions: minute, hour, day-of-month, month, day-of-week. Ranges (1-5), lists (1,3,5), step values (*/15), and names (MON, JAN) all parse. Quartz-style 6- or 7-field expressions are not generated. Paste the output into the Cron Parser for the next five fire times.

How do the curl converters handle authentication headers?

Headers pass through verbatim. If your curl command contains -H "Authorization: Bearer ..." or -u user:pass, the output from curl to fetch, curl to Python requests, or curl to PHP cURL keeps the equivalent header or auth tuple. Scrub secrets before pasting into chat, docs, or a shared branch.

Can I use these tools without an internet connection?

After a tool's page loads once, most keep running offline for that session, the logic is client-side. Close the tab and you'll need a connection to reopen. For a repeatable offline workflow, bookmark the five or six utilities you use most.

For byte-level transforms like base64, URL encoding, or hashing, head to Encoding Tools. For JSON, CSV, XML, or YAML reshaping, Data Tools is the right stop. For case changes, slug conversion, and find-and-replace, Text Tools sits alongside this page.