Xerobit
Category 3 of 7

Dev Productivity Tools

The daily-driver utilities. Regex testing with live match highlighting, cron expressions that actually explain themselves, timestamp conversion across units and timezones, HTTP status code reference, and a color picker with WCAG contrast, all client-side, all fast.

8 free tools No signupRuns 100% in your browser

Subnet / CIDR Calculator

Calculate IPv4 subnets, network, broadcast, usable range, wildcard mask. Input CIDR (/24) or dotted mask (255.255.255.0). Binary visualization.

subnet calculatorDev Productivity

Regex Tester

Test regular expressions with live match highlighting and explanation.

regex testerDev Productivity

Timestamp Converter

Convert Unix timestamps, epoch seconds/milliseconds, and ISO 8601 dates.

epoch converterDev Productivity

HTTP Status Codes

Full HTTP status code reference with explanations and when to use each.

http status codesDev Productivity

Email Signature Generator

Build a professional plain text email signature by entering your name, job title, company and contact information.

email signature generatorDev Productivity

User Agent Parser

Parse any User-Agent string into browser, OS, device, and engine. Or detect your own. Built on the maintained ua-parser-js dataset.

user agent parserDev Productivity

Cron Builder

Build and parse cron expressions with human-readable explanations.

cron expression generatorDev Productivity

Chmod Calculator

Tick read, write and execute for owner, group and other to get octal, symbolic and the full chmod command.

chmod calculatorDev Productivity

What this pillar is really about

These are the little-utilities-that-you-use-daily. Not because they're exciting, but because every working engineer needs them 10 times a week and the existing options bury the tool under ads, send your data to a server, or just aren't quite right.

None of these is novel, regex testers and cron builders have existed for decades. What makes these worth using: they're fast, correct, and stay out of your way. You land on the page, the tool works, you leave.

Everyday workflows that chain these tools

  • Debugging a log file: paste a sample line into Regex Tester → extract the timestamp → paste it into Timestamp Converter → confirm it's in the right timezone.
  • Scheduling a job: build the schedule in Cron Builder → copy the expression → paste into your crontab or CI config.
  • Debugging an API response: get a weird status code → check the HTTP Status Codes reference → realize the difference between 401 and 403.
  • Design-dev handoff: designer sends a hex → check Color Picker's WCAG contrast against your background → red-flag if below AA.

Design principles across the pillar

  • No sign-up, no ads over UI. Every tool works the instant you land.
  • Explain, don't just compute. Cron builder shows the human-readable explanation AND the next 5 runs. HTTP codes page shows why 422 isn't 400.
  • Live by default. Type and see. No "Run" button unless there's a reason (Hash Generator auto-runs, Regex Tester auto-runs).
  • Standards-accurate. WCAG 2.1 contrast uses the real linear-sRGB luminance formula. Cron uses POSIX OR semantics for DOM/DOW, matching cron behavior.

All 8 tools in this category

  • Subnet / CIDR Calculator: Calculate IPv4 subnets, network, broadcast, usable range, wildcard mask. Input CIDR (/24) or dotted mask (255.255.255.0). Binary visualization.
  • Regex Tester: Test regular expressions with live match highlighting and explanation.
  • Timestamp Converter: Convert Unix timestamps, epoch seconds/milliseconds, and ISO 8601 dates.
  • HTTP Status Codes: Full HTTP status code reference with explanations and when to use each.
  • Email Signature Generator: Build a professional plain text email signature by entering your name, job title, company and contact information.
  • User Agent Parser: Parse any User-Agent string into browser, OS, device, and engine. Or detect your own. Built on the maintained ua-parser-js dataset.
  • Cron Builder: Build and parse cron expressions with human-readable explanations.
  • Chmod Calculator: Tick read, write and execute for owner, group and other to get octal, symbolic and the full chmod command.

Further reading

Other categories

  • Data & Format: JSON, XML, YAML, CSV, SQL, HTML and Markdown: format, view, convert and diff.
  • Encoding & Crypto: Base64, URL, JWT, hashes, UUID, binary, QR codes and passwords.
  • Frontend & Design: CSS generators, color tools, image tools, favicons and px to rem.
  • Text Tools: Counters, case converters, cleaners, formatters and everyday text utilities.
  • Fonts & Symbols: Fancy text, text effects, copy and paste symbols, emoticons and special characters.
  • Name Generators: Names for people, pets, bands, teams, businesses, characters and usernames.
  • Random & Games: Random pickers, dice, coin flips, wheels, party games and test data generators.
  • Math Calculators: Algebra, fractions, factors, exponents, logarithms and everyday arithmetic.
  • Geometry: Area, perimeter, volume and surface area of shapes, plus triangles and coordinates.
  • Statistics & Probability: Averages, deviation, distributions, hypothesis tests, probability and combinatorics.
  • Finance: Loans, interest, investing, margins, taxes, salary and business calculators.
  • Health & Fitness: BMI, calories, macros, heart rate, hydration and training calculators.
  • Date & Time: Dates, durations, ages, business days, calendars and time arithmetic.
  • Science & Engineering: Physics, chemistry and electrical formulas with the working shown.
  • Construction & DIY: Concrete, paint, flooring, roofing, lumber and home improvement estimators.
  • Education & Grades: Grade, GPA and exam calculators and study helpers.
  • Length & Distance: Convert meters, feet, inches, miles, kilometers and every other length unit.
  • Weight & Volume: Convert kilograms, pounds, ounces, liters, gallons, cups and cooking measures.
  • Temperature, Speed & Data: Temperature, speed, pressure, energy, power and digital storage converters.