Developer Tools Calculators & Tools
JSON, Base64, Hash, Regex, API, UUID generators, formatters, and validators for developers.
These developer utilities handle the small, repetitive tasks that come up while coding: formatting, encoding, hashing, and validating. Everything runs in your browser, so you can paste, transform, and copy without sending data anywhere.
Apache Log Parser, Free Online Developer Tool
Parse Apache/NGINX combined access log lines into IP, time, request, status and size fields. Get instant results, the formula, and a clear example.
API Key Generator
Generate random, secure API keys and tokens with an optional prefix. Cryptographically secure.
Mock JSON Generator
Generate mock JSON API responses, arrays of fake records with common fields, for front-end testing.
Barcode Validator
Validate EAN-13, EAN-8 and UPC-A barcode numbers using their check digit.
Image to Base64
Convert an image to a Base64 data URI you can embed directly in HTML or CSS.
Base64 Encode / Decode
Encode text to Base64 or decode Base64 back to text instantly. Free online Base64 tool with UTF-8 support.
Bcrypt Hash Generator
Generate bcrypt password hashes in your browser with a configurable cost factor. Free online bcrypt tool.
UUID Generator (Bulk)
Generate one or many version-4 UUIDs at once. Cryptographically random, RFC 4122 compliant.
Byte Array ⇄ String
Convert a string to a byte array (UTF-8) or a byte array back to a string. Supports decimal byte lists.
Checksum Calculator
Calculate the SHA-256 checksum of text or a file to verify integrity. Free online checksum tool.
Code Beautifier
Beautify and indent JSON or CSS code automatically. Clean up minified or messy code.
Code Diff
Compare two blocks of code line by line and see added, removed and changed lines.
Code Minifier
Minify JSON or CSS code by removing whitespace and comments. Auto-detects the language.
Color Shade Generator
Generate a palette of tints and shades from a base hex color. Great for design systems.
CORS Header Builder
Build the right CORS response headers for your API by choosing allowed origins, methods and headers.
Credit Card BIN Lookup
Detect the card brand and type from the first digits (BIN/IIN) of a card number. For testing only.
Credit Card Validator
Validate a credit card number using the Luhn algorithm and detect the card brand. For testing only.
Cron Expression Generator
Build cron expressions from simple schedule choices and see a plain-English description. Free online cron builder.
Cron Parser
Parse a cron expression into a plain-English description of when it runs.
CSRF Token Generator
Generate cryptographically secure random CSRF tokens for forms and APIs.
CSS Minifier
Minify CSS by removing comments, whitespace and the last semicolons. Shrink stylesheets instantly.
CSS Property Reference
Searchable reference of common CSS properties and what they do.
CSV Analyzer
Analyze a CSV, row and column counts, column names, and basic per-column stats.
CSV Formatter
Format CSV into a clean, aligned table view for easy reading. Free online CSV formatter.
Large CSV Viewer
View large CSV data as a table in your browser, processed locally for privacy.
CSV ⇄ TSV
Convert CSV to TSV (tab-separated) and back instantly. Free online CSV/TSV converter.
CSV Validator
Validate CSV structure, checks that every row has the same number of columns as the header.
CSV Viewer
View CSV data as a clean HTML table in your browser. Free online CSV viewer.
cURL to Code
Parse a cURL command into its method, URL, headers and body. Understand any curl request.
Data URI Parser
Parse a data: URI to reveal its MIME type, encoding and decoded content. Free online data URI inspector.
Date Calculator
Add or subtract days, weeks, months, or years from any date. Free online date calculator.
Email Header Analyzer
Analyze raw email headers, sender, recipient, subject, route hops and authentication results.
Email Validator
Validate email address syntax instantly. Checks format against the standard email pattern.
Epoch Countdown
See a live countdown to a chosen Unix timestamp, and how long until or since it.
String Escape / Unescape
Escape or unescape strings for JSON, JavaScript and code, handle quotes, backslashes, newlines and tabs.
Excel Formula Reference
Searchable reference of common Excel/Google Sheets formulas and what they do.
Fake Data Generator
Generate fake names, emails, addresses and phone numbers for testing. Free online mock data generator.
File Signature Checker
Detect a file type from its magic-number signature, regardless of file extension.
GraphQL Formatter
Format and indent GraphQL queries with proper bracket nesting. Clean up messy GraphQL.
GraphQL Query Builder
Wrap a GraphQL query into a valid JSON request body and a cURL command for your endpoint.
Hash Generator (MD5, SHA-1, SHA-256)
Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text instantly in your browser.
Hash Identifier
Identify the likely hash algorithm (MD5, SHA-1, SHA-256, bcrypt and more) from a hash string by its length and format.
Hex Encoder / Decoder
Convert text to hexadecimal or decode hex back to text instantly. UTF-8 aware online hex tool.
HMAC Generator
Generate HMAC signatures (SHA-256, SHA-1, SHA-512) from a message and secret key. Free online HMAC tool.
.htaccess Generator
Generate common .htaccess rules, force HTTPS, www redirect, and caching, with checkboxes.
HTML Entity Encoder / Decoder
Encode text to HTML entities or decode HTML entities back to text. Free online HTML entity tool.
HTML Minifier
Minify HTML by removing comments and collapsing whitespace. Reduce page size instantly.
HTML Preview
Preview HTML rendered live in a sandboxed frame. See how your markup looks instantly.
HTML Validator
Check HTML for basic issues, unclosed tags and mismatched nesting. Free online HTML checker.
HTTP Headers Explained
Searchable reference of common HTTP request and response headers and their purpose.
HTTP Header Parser
Parse raw HTTP headers into clean key-value pairs. Free online HTTP header parser.
HTTP Request Builder
Build a cURL command from a method, URL, headers and body. Copy and run it in your terminal.
HTTP Status Codes
Searchable reference of HTTP status codes (200, 301, 404, 500 and more) with meanings.
IBAN Validator
Validate an International Bank Account Number (IBAN) using the official mod-97 checksum.
IP Address Info
Validate an IPv4 or IPv6 address, see its class, and whether it is private or public.
ISBN Validator
Validate ISBN-10 and ISBN-13 book numbers using their official checksum digits.
ISO 8601 Converter
Convert between ISO 8601 datetimes, Unix timestamps and human-readable dates.
JavaScript Minifier
Minify JavaScript by removing comments and extra whitespace. A quick, safe basic minifier.
JSON Diff
Compare two JSON objects and see which keys were added, removed or changed.
JSON File Viewer
Open and pretty-print a JSON file in your browser. View large JSON files safely and privately.
JSON Formatter
Format, beautify and validate JSON with proper indentation. Shows clear error messages for invalid JSON.
JSON Key Explorer
List every key path in a JSON object using dot/bracket notation. Great for finding nested fields.
JSON Minifier
Minify JSON by removing all unnecessary whitespace, producing the smallest valid JSON.
JSON Schema Generator
Generate a JSON Schema (draft-07) from a sample JSON object automatically.
JSON Tree Viewer
Visualize JSON as an indented tree showing keys, types and values. Free online JSON tree viewer.
JSON Validator
Validate JSON and get clear, precise error messages. Free online JSON validator.
JWT Generator
Generate a signed JSON Web Token (HS256) from a payload and secret, in your browser.
JWT Decoder
Decode a JSON Web Token (JWT) to view its header and payload. Does not verify the signature.
Log Analyzer
Analyze access logs, count status codes, top IPs and top URLs from pasted log lines.
Log Viewer
View and filter log lines by keyword or level (ERROR, WARN, INFO). Free online log viewer.
Lorem Ipsum Generator
Generate Lorem Ipsum placeholder text, paragraphs, sentences or words. Free online dummy text generator.
MIME Types Reference
Searchable list of common MIME types and the file extensions they map to.
NanoID Generator
Generate compact, URL-safe NanoIDs, a smaller, faster alternative to UUIDs. Configurable length.
NGINX Log Parser
Parse NGINX combined access log lines into IP, time, request, status and size fields.
Password Generator
Generate strong, random, secure passwords with custom length and character sets. Cryptographically secure and 100% private.
Password Strength Checker
Check how strong a password is based on length, character variety and common patterns. 100% private.
Phone Number Formatter
Format and normalize phone numbers, including US (XXX) XXX-XXXX and E.164 formats.
Common Ports Reference
Searchable reference of common TCP/UDP port numbers and the services that use them.
Query String Builder
Build a URL-encoded query string from key=value lines. Encodes special characters safely.
Query String Parser
Parse a URL query string into key-value pairs. Decodes percent-encoding automatically.
Random Hex Generator
Generate random hexadecimal strings of any length. Cryptographically secure, great for tokens and IDs.
Regex Builder
Build common regular expressions from simple options, digits, letters, email, ranges and anchors.
Regex Cheat Sheet
Searchable regex cheat sheet, metacharacters, quantifiers, classes and anchors with examples.
Regex Explainer
Explain a regular expression token by token in plain English.
Common Regex Patterns
Ready-to-use regex patterns for emails, URLs, phone numbers, dates and more.
Regex Tester
Test regular expressions against sample text and see all matches highlighted, with flags.
REST Client (cURL Builder)
Build REST API requests as cURL commands, method, URL, headers and JSON body.
Robots.txt Validator
Check a robots.txt file for common syntax issues, directives, user-agents and sitemap lines.
ROT13 Encoder / Decoder
Apply the ROT13 letter-substitution cipher to text. ROT13 is its own inverse, so the same action encodes and decodes.
SQL Error Lookup
Searchable reference of common MySQL and PostgreSQL error codes and what they mean.
SQL Query Formatter
Format and beautify SQL queries with uppercase keywords and clause-based line breaks.
Tailwind Class Generator
Find the Tailwind CSS spacing class for a pixel value, and convert rem/px quickly.
Timestamp Generator
Generate the current Unix timestamp, milliseconds and ISO 8601 datetime instantly. Free online timestamp tool.
Timezone Converter
Convert a date and time from one timezone to another using the browser timezone database.
JWT Token Visualizer
Visualize the three parts of a JWT, header, payload and signature, colour-decoded.
Unicode Escape / Unescape
Convert text to \u Unicode escape sequences or decode them back to characters.
Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and back. Supports seconds and milliseconds.
URL Encoder / Decoder
Encode or decode URLs and query parameters (percent-encoding) instantly. Free online URL encoder.
URL Parser
Break a URL into its components: scheme, host, port, path, query and fragment.
URL Validator
Validate whether a string is a well-formed URL. Checks scheme, host and structure.
UUID Validator
Validate a UUID and detect its version (1-5). Checks RFC 4122 format.
VIN Validator
Validate a Vehicle Identification Number (VIN) using the North American check-digit formula.
Webhook Payload Builder
Build a sample webhook POST request (JSON body + cURL) to test your endpoint locally.
XML Formatter
Format and indent XML for readability. Pretty-print messy XML instantly.
XML to JSON
Convert XML to JSON instantly in your browser. Free online XML to JSON converter.
XML Minifier
Minify XML by removing whitespace between tags. Produce compact XML instantly.
XML Validator
Validate XML for well-formedness and see precise parser errors. Free online XML validator.
YAML Formatter
Format and normalize YAML with consistent 2-space indentation. Free online YAML beautifier.
YAML ⇄ JSON
Convert YAML to JSON and JSON to YAML instantly. Free online YAML/JSON converter.
YAML Validator
Validate YAML syntax and see clear error messages. Free online YAML validator.
How to choose the right Developer Tools tool
- Working with data formats? Use the JSON and Base64 tools.
- Need a checksum or token? The hash and UUID generators cover that.
- Testing patterns? The regex tester shows matches as you type.
- Each tool does one job well, so pick the one that matches your task.
Who these tools are for
For developers, students learning to code, and anyone who needs a quick, private utility without installing anything.
Need Help Solving a Problem?
Our AI Math Solver handles any math problem, just type it in plain English and get instant step-by-step solutions.
Explore Other Categories
Popular tools from our other scientific categories
Absolute Value Calculator
Calculate the absolute value of any number. Use this free calculator for fast, accurate answers, complete with the formula and a worked example.
AC to DC Converter Calculator
Convert AC voltage to DC voltage for different rectifier configurations. Free online calculator with instant, step-by-step results.
Acid-Base Titration Calculator
Calculate concentration from titration data. Get quick, accurate results with this free online calculator, including formulas and worked examples.
ABV Calculator
Calculate alcohol by volume from original and final gravity. Free calculator with instant calculations, the underlying formula, and an easy-to-follow example.
Amortization Schedule Calculator - Free Online
Free Generate a complete amortization schedule. Step-by-step solutions and formulas included. Free, accurate results with step-by-step explanations.
Average Cost Basis Calculator - Free Online
Free Calculate average cost per share. Step-by-step solutions and formulas included. Fast, accurate, and free, with formula and example.
1031 Exchange Calculator - Free Online
Free Calculate tax deferral in a 1031 exchange. Step-by-step solutions and formulas included. Fast, accurate, and free, with formula and example.
A1C Calculator - Free Online
Free Convert between A1C percentage and estimated average glucose. Step-by-step solutions and formulas included. Simple, fast, and free.
Batting Average Calculator
Calculate batting average in baseball/cricket. Free calculator with instant calculations, the underlying formula, and an easy-to-follow example.
Air Density Calculator
Calculate air density from temperature and pressure using the ideal gas law. Fast, accurate, and free, with formula and example.
Age Calculator
Calculate exact age in years, months, and days. Use this free calculator for fast, accurate answers, complete with the formula and a worked example.
Acceleration Converter
Convert between acceleration units. Get quick, accurate results with this free online converter, including formulas and worked examples.
Circle Area Calculator
Calculate the area and circumference of a circle. Free online calculator with instant results, step-by-step explanations, and a clear worked example.
Angle Between Two Lines Calculator
Calculate the angle between two lines given their slopes. Free calculator with instant calculations, the underlying formula, and an easy-to-follow example.
Add Text to Beginning, Free Online Text Tool
Add custom text to the beginning of every line in your text instantly. Get instant results, the formula, and a clear example.
Accessible Color Pair Finder
Check if a text/background pair meets WCAG and suggest a fix. Free tool with instant calculations, the underlying formula, and an easy-to-follow example.