Free Online Developer Tools — Format, Validate & Convert
Fast, private, 100% client-side utilities for JSON, XML, SQL, YAML, CSV, Base64, JWT, LLM tokens, prompts, and more. No signup. No uploads.
CodingFormatter is a free suite of online tools to format, validate, and convert JSON, XML, SQL, YAML, and related files entirely in your browser. Search a tool above or browse the categories below.
There is no signup and nothing is uploaded. Your data never leaves this device. AI utilities such as the JSON Schema validator also run locally.
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.
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 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 structured data and code.
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 →Validate syntax and catch errors before they reach production.
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.
Converters
View all →Convert between JSON, YAML, CSV, XML, and more - instantly in your browser.
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 internationalized domain names between Unicode and Punycode.
Encoders & Utilities
View all →Encode, decode, and inspect tokens, Base64, and other web utilities.
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, lint prompts, and validate structured LLM output - 100% client-side.
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.