Free Online Developer Tools - Format, Validate, Convert, Encoder & Util's, AI & LLM Tool's
Free, private, 100% client-side tools across formatters, validators, converters, encoders, and AI/LLM utilities. Format JSON and SQL, validate YAML and regex, convert CSV and Unix timestamps, inspect JWTs, count LLM tokens—and more. No signup. No uploads.
CodingFormatter is a free suite of online developer tools that run entirely in your browser. Use them to format and minify structured data, validate syntax before shipping, convert between common formats, encode or inspect web payloads, and support day-to-day LLM prompt work—without creating an account.
Browse five categories: Formatters (JSON, XML, HTML, SQL, and HTML Beautifier), Validators (YAML, JavaScript, regex, HTML, links, redirects, JSONPath/XPath, and Diff Checker), Converters (CSV, JSON, YAML, XML, SQL, colors, images, IDN, and Epoch Converter), Encoders & Utilities (Base64, JWT, HAR Sanitizer, entity escapers, and SVG Viewer), and AI & LLM Tools (token counting, context windows, prompt linting/diff/minify, schema helpers, and embedding similarity).
Everything processes locally with JavaScript. Sensitive configs, tokens, prompts, and logs never leave this device. Search above for a tool by name, or scroll to popular picks and full category lists below.
Need structured-output checks for model responses? Try the client-side LLM JSON Schema Validator (powered by local Ajv against the JSON Schema standard) alongside the rest of the AI toolkit.
Popular tools
Pretty-print, minify, and validate JSON online.
Pretty-print, minify, and validate XML markup.
Format and minify HTML with syntax-aware indentation.
Beautify SQL across MySQL, PostgreSQL, T-SQL, and more.
Validate YAML syntax with precise line and column errors.
Convert CSV or TSV into a JSON array of objects.
Convert JSON objects to clean YAML.
Convert YAML documents to pretty-printed JSON.
Encode text to Base64 with full UTF-8 support.
Decode JWT header and payload - never sent to a server.
Beautify HTML with indent, wrap length, and attribute controls.
Test regex patterns against sample text with match offsets and capture groups.
Evaluate JSONPath expressions against JSON documents.
Compare two text or code files side-by-side or unified.
Generate Java POJO classes from JSON.
Convert XML to JSON with attribute prefixes.
Generate SQL INSERT statements from CSV.
Convert images to Base64 data URIs in your browser.
Convert Unix timestamps to dates and back with timezones and a live clock.
Convert internationalized domain names between Unicode and Punycode.
Redact secrets from HAR archives before sharing.
Preview SVG markup safely in your browser.
Count GPT tokens across models. 100% client-side.
Compare two prompt versions with a line or word diff. 100% client-side.
Validate structured LLM JSON output against a JSON Schema. Client-side Ajv.
Formatters
View all →Pretty-print, minify, and beautify JSON, XML, HTML, and SQL with consistent indentation—entirely in your browser.
Pretty-print, minify, and validate JSON online.
Pretty-print, minify, and validate XML markup.
Format and minify HTML with syntax-aware indentation.
Beautify SQL across MySQL, PostgreSQL, T-SQL, and more.
Beautify HTML with indent, wrap length, and attribute controls.
Validators
View all →Check YAML, JavaScript, HTML, regex, JSONPath, XPath, links, and redirects, or compare files with Diff Checker before you ship.
Validate YAML syntax with precise line and column errors.
Check JavaScript syntax without executing your code.
Test regex patterns against sample text with match offsets and capture groups.
Evaluate JSONPath expressions against JSON documents.
Evaluate XPath against XML or HTML in your browser.
Structural HTML lint - unclosed tags, duplicate ids, and common issues.
Check URL reachability and redirect hints from your browser.
Bulk-check links extracted from HTML or a URL list.
Find JSONPath expressions for a key or value in JSON.
Compare two text or code files side-by-side or unified.
Converters
View all →Convert between CSV, JSON, YAML, XML, SQL, colors, images, IDN domains, and Unix timestamps—instantly and privately.
Convert CSV or TSV into a JSON array of objects.
Convert JSON objects to clean YAML.
Convert YAML documents to pretty-printed JSON.
Generate a draft .proto schema from sample JSON.
Generate Java POJO classes from JSON.
Convert JSON objects to XML markup.
Convert JSON to PHP array syntax.
Generate C# classes from JSON.
Generate a draft XSD schema from sample XML.
Convert XML documents to YAML.
Convert XML to JSON with attribute prefixes.
Convert basic SELECT queries to MongoDB find().
Convert INI config files to JSON.
Convert INI files to XML markup.
Convert INI files to YAML.
Convert CSV rows to XML elements.
Convert CSV to a YAML list of records.
Generate SQL INSERT statements from CSV.
Convert images to Base64 data URIs in your browser.
Preview and inspect image data URIs.
Convert RGB, RGBA, or HSL colors to hex with a live swatch.
Convert hex colors to RGB/RGBA with a live swatch.
Convert Unix timestamps to dates and back with timezones and a live clock.
Convert internationalized domain names between Unicode and Punycode.
Encoders & Utilities
View all →Base64 encode/decode, inspect JWTs, sanitize HAR archives, escape HTML/JS/XML strings, and preview SVG safely.
Encode text to Base64 with full UTF-8 support.
Decode Base64 to UTF-8 text safely in your browser.
Decode JWT header and payload - never sent to a server.
Redact secrets from HAR archives before sharing.
Encode or decode HTML entities in your browser.
Escape or unescape JavaScript string contents.
Escape or unescape XML special characters.
Preview SVG markup safely in your browser.
AI & LLM Tools
View all →Count tokens, size context windows, lint and diff prompts, validate LLM JSON schemas, and compare embeddings—no API keys.
Count GPT tokens across models. 100% client-side.
See how much of a model context window a prompt plus expected output would use.
Compare two prompt versions with a line or word diff. 100% client-side.
Validate structured LLM JSON output against a JSON Schema. Client-side Ajv.
Infer an OpenAI or Anthropic tool schema from sample JSON.
Lint mustache, Jinja, and LangChain prompt templates for delimiter and variable issues.
Compute cosine similarity, dot product, and Euclidean distance for two embedding vectors.
Strip markdown and extra whitespace from prompts to save tokens.