Developer Tools

UUID Generator — Bulk v4 Generation, No-Hyphens & Uppercase Formats

Generate any number of UUID v4 (random) identifiers in bulk, right in your browser. One click converts to standard, uppercase, no-hyphens, braces, or URN format, ready to copy. Free, no sign-up required.

Nano ID Generator

Generate URL-safe, short, unique IDs in bulk right in your browser. Choose the character set (default, alphanumeric, lowercase, uppercase, digits, or hex) and length freely — ideal when you need something shorter than a...

ULID Generator

Generate ULIDs in bulk — sortable, time-ordered identifiers that work as a drop-in alternative to UUIDs.

UUID v7 Generator

Generate UUID v7 in bulk in your browser — the RFC 9562 standard that embeds a 48-bit millisecond timestamp so IDs sort in creation order. Standard, uppercase, no-hyphens, braces, and URN formats all supported, and it dr...

UUID v7 Timestamp Decoder

Extract the millisecond timestamp embedded in the first 48 bits of a UUID v7, converting it back to a UTC date and time by simply pasting the string. Detects non-v7 versions and variant anomalies, and works as the revers...

JSON Formatter

Format, minify, and validate JSON. Choose an indent level to pretty-print for readability, or compress to a single line. Syntax errors are highlighted instantly.

SQL Formatter

Format SQL text for better readability.

URL Parser

Enter a URL to break it down into protocol, host, path, query parameters, and fragment. Tracking parameters such as utm_source are automatically detected.

JSON Lines (JSONL) ⇔ JSON Array Converter

Convert between JSON Lines format — one JSON object per line — and a standard JSON array. Handy for checking machine learning datasets and log output.

JSON to TypeScript Type Converter

Paste a JSON object (or JSON array) to automatically generate the corresponding TypeScript interface/type definitions.

JSON to Go Struct Converter

Paste a JSON object (or JSON array) to automatically generate the corresponding Go struct definitions with json tags.

XML Formatter

Pretty-print, minify, and validate XML on the spot — check for well-formedness errors instantly. Also handy for inspecting SOAP/REST API responses and RSS/Atom feeds.

YAML Formatter

Format YAML with a consistent indent width, or convert it to JSON. Detects tab characters and inconsistent indentation.

TOML Formatter

Format and validate TOML (Tom's Obvious, Minimal Language). Neatly aligns key = value pairs, tables, and arrays, and reports syntax errors with line numbers.

YAML to JSON Converter

Convert YAML data to JSON. Instantly turn structures written in YAML — Kubernetes manifests, docker-compose.yml, CI config files — into a format that JSON-only tools like jq can work with, right in your browser.

Go Struct to JSON Sample Generator

Paste a Go struct definition with json tags to automatically generate matching sample JSON data. Supports nested structs, slices, omitempty, and json:"-", handy for API mocks and Postman examples.

JSON Diff Checker

Compare two JSON documents and instantly see which keys were added, removed, or changed, listed by key path. Objects and arrays are walked recursively, and even type mismatches are reported as changes. Everything runs in...

XML to JSON Converter

Convert XML data to JSON. Turn legacy XML API responses, SOAP payloads, or RSS/Atom feeds into JSON — attributes go under @attributes, text under #text, repeated elements become arrays — right in your browser.

JSON to XML Converter

Convert JSON data to XML. @attributes becomes element attributes, #text becomes text content, and arrays become repeated sibling elements — the reverse of our XML-to-JSON converter, right in your browser.

CSV Viewer

Format and show selected CSV file on display.

Convert JSON to CSV

Convert array of object in JSON format to CSV.

CSV to JSON Converter

Convert a CSV file into a JSON array of objects. Choose the delimiter and whether the first row is a header, then copy or download the result. Everything runs in your browser — nothing is sent to a server.

CSV to SQL Converter (INSERT Statement Generator)

Convert CSV files into SQL INSERT and CREATE TABLE statements. Supports MySQL, PostgreSQL, and SQLite dialects with automatic column type detection (integer, decimal, string). Conversion runs entirely in your browser; no...

CSV to Markdown Table Converter

Convert CSV files into Markdown table syntax (`| col1 | col2 |`). Choose the delimiter, whether to use the first line as a header, and column alignment (left, center, right). The result can be copied or downloaded. Conve...

Markdown Table to CSV Converter

Convert a Markdown table (`| col1 | col2 |`) into CSV or TSV. Handy for pulling tables exported from GitHub Wiki, Notion, or Confluence into Excel or a spreadsheet. Conversion runs entirely in your browser; no data is se...

CSV to HTML Table Converter

Convert CSV files into an HTML snippet using <code>&lt;table&gt;&lt;tr&gt;&lt;td&gt;</code> markup. Choose the delimiter, whether to use the first line as a header, and whether to wrap the rows in <code>&lt;thead&gt;</co...

HTML Table to CSV Converter

Paste a source containing an HTML <code>&lt;table&gt;</code> tag to convert it into CSV/TSV. Handy when you want to copy a table from another site into a spreadsheet. Header rows inside thead are automatically recognized...

CSV to XML Converter

Paste CSV/TSV data to convert it into XML, where each row becomes a <row> element (format: <row><column1>value</column1>...</row>).

CSV to Excel Converter

Convert CSV/TSV files to Excel (.xlsx) format. Files are processed entirely in your browser and never sent to a server.

Excel to CSV Converter

Convert an Excel (.xlsx) file to CSV format. The file is processed entirely in your browser and is never sent to a server.

CSV Diff Checker

Compare two CSV files and instantly see added rows, removed rows, and changed cells. Pick any column as the row key to match rows, view before/after values side by side, and compare CSVs with different column layouts. Ev...

XML to CSV Converter

Paste XML text with repeating <row><column1>value</column1>...</row> records and convert it to CSV/TSV.

CSV ⇔ JSON Lines (JSONL) Converter

Convert between CSV files and JSON Lines (JSONL, one JSON object per line). Choose your delimiter, and rows with inconsistent keys are merged automatically. Conversion runs entirely in your browser; nothing is sent to a...

Base64 Encode / Decode — Free, No Sign-up

Free tool to encode text to Base64 or decode it back, switching modes in one click. Useful for email attachments and JWT tokens. Runs in your browser — nothing sent to a server.

ASCII Code Table (Free) — Character to Code Converter

Free, complete ASCII code table (0–127) with an instant character-to-code converter. Look up decimal, hex, octal, and binary values, plus control character descriptions — a handy developer reference.

Line break at a specified length

Insert a line break at a specified length.

HTML Escape / Unescape

Convert special characters like &, <, >, ", and ' into HTML entities (escape), or convert entities back to their original characters (unescape). Useful for XSS prevention and embedding text in HTML.

Mojibake Converter & Fixer — Character Encoding Repair Tool

Paste garbled (mojibake) text to instantly detect the encoding mismatch that caused it, with ranked repair candidates. Also converts explicitly between UTF-8, Shift_JIS, EUC-JP, and JIS (ISO-2022-JP) — free, no sign-up r...

Remove Line Breaks Tool

Remove, replace, or clean up line breaks in text in bulk. Useful for fixing text copied from PDFs or Excel where breaks appear mid-word, or for preparing text for CSV cells and single-line logs. It can also convert line...

SNS Character Counter (Twitter/X-style Count)

A character counter that follows X (formerly Twitter)'s weighted counting rule. Full-width characters count as 2, half-width characters count as 1, and the tool shows how many characters remain before the 280-character l...

Extension ↔ MIME Type Converter

Look up and convert between file extensions and MIME types (Content-Type) in either direction. Type ".png" or "png" to see its MIME type, or "image/png" to see its matching extensions. Includes a reference table of about...

Unicode / Character Code Cross-Reference

Free tool that shows a character's Unicode code point, UTF-8 byte sequence, and JavaScript/HTML/URL/CSS escape representations side by side. Everything runs in your browser.

File to Base64 Converter (with data URI support, both directions)

Convert any file (image, PDF, and more) to a Base64 string or data URI, or decode a Base64 string / data URI back into a downloadable file. Everything runs in your browser — files are never sent to a server.

.htpasswd File Generator

Generate .htpasswd files for Apache and Nginx Basic Authentication securely in your browser. Supports bcrypt, APR1-MD5, and SHA-1. Passwords are never sent to the server.

CSP Header Validator

Paste a Content-Security-Policy header value to validate its directives and source values in one pass. Detects risky settings like unsafe-inline, a missing default-src fallback, and typos in directive names, and shows ev...

Security Headers Checker

Enter any site URL to check whether key security headers such as HSTS, CSP, and X-Frame-Options are properly configured. See which headers are missing or weak, along with tips for fixing each one.

.htaccess Syntax Checker

Paste the contents of an .htaccess file to instantly catch common mistakes: unclosed block tags, misspelled directive names, RewriteRule with too few arguments, and dangling RewriteCond lines.

Test Card Numbers for Stripe, PayPal, Braintree & Square (2026 List)

Up-to-date test and dummy credit card numbers for Stripe, PayPal, Square, and Braintree. Organized by brand and success/failure pattern, with one-click copy for fast payment integration testing.

Credit Card Number Validator | Luhn Algorithm & Brand Detection

Enter a credit card number to verify its check digit with the Luhn algorithm and automatically detect the brand (Visa, Mastercard, Amex, etc.). Handy for testing form validation.

Dummy File Generator

Generate dummy files of an exact byte size — images, audio, video, PDFs, text, and more — entirely in your browser. Handy for testing upload form size limits. Files are never sent to a server.

Sample CSV (Dummy Data) Generator

Define column names and types (sequential ID, full name, email, date, numbers, and more) to instantly generate and download dummy CSV data for testing and QA.

Regex Tester

Enter a regular expression pattern and a test string to highlight matches and list capture group values. Supports the g/i/m/s/u flags using JavaScript's native RegExp.

Text Diff Comparison

Compare two blocks of text line by line and see added and removed lines highlighted in color. Useful for checking config file changes, proofreading documents, or reviewing code without Git. All diffing happens in your br...

List Compare Tool (Common & Unique Lines)

Compare two text lists (one item per line) and instantly extract the lines common to both, the lines only in A, and the lines only in B using set operations. Useful for matching mailing lists or checking inventory duplic...

URL Slug Generator

Convert any text into a URL-safe slug (kebab-case) made only of lowercase letters, digits, and hyphens. Includes an optional simplified Japanese romanization mode for hiragana and katakana.

Cron Expression Parser & Next Run Calculator

Parse a cron expression (minute hour day month weekday) and see a plain-English description of its schedule. Supports steps, ranges and lists, and calculates the next 5 run times. Handy for reading crontab entries or a G...

Cron Expression Builder

Build a cron expression just by picking minute, hour, day, month and weekday from dropdowns and number inputs. Preview the generated cron string, a plain-English description, and the next 5 run times instantly — handy fo...

Cron Expression to systemd Timer Converter

Free tool to convert a cron expression (minute hour day month weekday) into systemd timer OnCalendar= syntax. Warns about the day-of-month/day-of-week OR-semantics caveat, useful for migrating cron jobs to Docker/Kuberne...

systemd Timer to Cron Expression Converter

Convert a systemd timer's OnCalendar= syntax to a cron expression (minute hour day month weekday) for free. The reverse of our "Cron to systemd Timer" converter. Supports named shortcuts (daily, weekly, etc.) and warns a...

robots.txt Validator

Paste your robots.txt content to check its syntax. Parses User-agent, Disallow, Allow, and Sitemap directives and visualizes crawler access rules.

Sitemap.xml Validator

Paste your sitemap.xml to validate it against the sitemaps.org protocol — checks the urlset namespace, required loc elements, lastmod/priority formatting, and Google's 50,000 URL limit.

OGP & Meta Tag Validator

Paste your HTML to validate Open Graph (OGP) and Twitter Card meta tags. Detects missing tags and bad og:image URLs, and previews the social share card.

JSON-LD Structured Data Validator

Paste HTML or raw JSON-LD to validate FAQPage, BreadcrumbList, and Article structured data. Instantly spot missing required properties and common Google Rich Results mistakes.

ads.txt Validator

Paste your ads.txt content to check its syntax instantly. Validates the DOMAIN, PUBLISHER_ID, and RELATIONSHIP (DIRECT/RESELLER) fields line by line, helping you correctly set up the file that guards against unauthorized...

Hreflang Tag Validator

Paste the hreflang tags from your HTML <head> to automatically detect common multilingual SEO mistakes: missing x-default, missing self-reference, invalid language codes, and duplicate declarations.

Web App Manifest (manifest.json) Validator

Paste your manifest.json to check whether it meets PWA installability requirements. Verifies required fields such as name, start_url, display, and icons, and flags missing maskable icons in a clear checklist.

Robots Meta Tag / X-Robots-Tag Validator

Paste the value of a <meta name="robots"> tag or an X-Robots-Tag header to validate its directives in one pass. Detects conflicting instructions like combining noindex with index, and malformed values such as an invalid...

security.txt Validator

Paste your security.txt (RFC 9116) content to detect syntax errors. Checks required fields like Contact and Expires and their value formats, so you can confirm it's correctly published at /.well-known/security-text.

JWT Decoder

Paste a JWT (JSON Web Token) to instantly decode its header and payload, including an expiration (exp) check. No signature verification is performed and no secret key is required.

JWT Encoder (Generate & Sign)

Generate an HMAC-signed JWT (JSON Web Token) from header and payload JSON using HS256, HS384, or HS512 — right in your browser. Nothing, including the secret, is ever sent to a server.

JWT Signature Verifier (RS256/ES256, Public Key Verification)

A developer tool that verifies JWTs (JSON Web Tokens) signed with RS256 or ES256 using an SPKI-format public key (PEM), right in your browser. It also decodes the header/payload and checks the expiry claim. Nothing you e...

Free Data Size Converter (Bytes, KB, MB, GB, TB)

Free data size converter. Enter a byte count to convert it into all common units — KB, MB, GB, TB, and more — at once. Shows both the decimal (SI, base-1000) and binary (IEC, base-1024) systems side by side, and explains...

Number Base Converter (Binary, Octal, Decimal, Hexadecimal)

Convert numbers between binary, octal, decimal, and hexadecimal. Uses BigInt so even very large integers are converted with no loss of precision.

Bitwise Operation Simulator (AND, OR, XOR, NOT, Shift)

Compute AND, OR, XOR, NOT, left shift, and right shift on two numbers and visualize exactly which bits changed on a binary grid. Supports 8/16/32-bit widths.

Byte Length Counter by Encoding

Measure how many bytes your text becomes in UTF-8, Shift_JIS, EUC-JP, UTF-16, and JIS (ISO-2022-JP). Useful for checking database column limits and legacy form input caps.

Binary Hex Editor | View and Edit Files in Hexadecimal

Drag and drop a file to view its contents as a byte-by-byte hex dump. Identify the true file type via magic bytes, edit individual bytes, and download the result. Nothing is ever uploaded to a server.

Unix Timestamp Converter

Convert between Unix timestamps (epoch seconds or milliseconds) and human-readable dates. Supports multiple timezones, an instant "now" fill, and relative time display for developers.

Two's Complement Calculator (Signed Integer Binary Converter)

Convert a signed decimal integer to its 8/16/32/64-bit two's complement binary pattern, or convert back the other way. Also shows the unsigned interpretation, hexadecimal notation, and detects out-of-range values.

IEEE 754 Converter — Float to Binary Bits (32/64-bit)

Convert between decimal numbers and IEEE 754 bit patterns (32-bit single or 64-bit double precision) instantly, in both directions. Color-coded sign, exponent, and mantissa make NaN, infinity, and subnormal values easy t...

ISO 8601 Duration Converter

Convert ISO 8601 duration notation (e.g. PT1H30M) to and from total seconds. Handy for decoding formats used by the YouTube API, AWS timeout settings, and podcast RSS feeds.

FP16 & bfloat16 Bit Pattern Visualizer

Visualize the bit patterns of half-precision floating point (FP16, IEEE 754 binary16) and bfloat16. Convert decimal to bits and back, with color-coded sign, exponent, and mantissa fields. Useful for learning about ML qua...