NV Toolkit — 185 free developer tools
Format, validate, and convert JSON, XML, YAML, CSV, HTML and CSS — or generate typed classes in 19 languages — in a premium workspace built on the VS Code editor. No signup, no limits, no uploads.
What this site is
One workspace for the data chores between the real work
A developer's day is full of small, annoying transformations: a minified API response that needs to be readable, a YAML manifest that fails on an invisible tab, a CSV export that has to become JSON, a payload that deserves real model classes instead of a hand-typed interface, a folder of screenshots that should be WebP. NV Toolkit collects 185 of those tools behind one consistent interface: the same editor, the same keyboard shortcuts, the same exact-position error reporting whether you are formatting XML or decoding a JWT.
The tools are built on the engines your own toolchain already uses — prettier, quicktype, js-beautify, the reference image codecs compiled to WebAssembly — so the output here matches what CI would produce. And because the site is fully static, there is no server to receive what you paste: everything runs on your machine. Read more about who builds it and how it is tested.
Private by design
Every tool runs entirely in your browser. Nothing you paste is ever uploaded, logged, or stored — verify it offline.
Instant results
Statically rendered pages served from the edge, with editors that load lazily. No spinners, no waiting.
A real editor
Powered by Monaco — the engine behind VS Code — with syntax highlighting, error squiggles, and precise diagnostics.
JSON Tools
19JSON Formatter
Format, beautify, and validate JSON instantly in a professional VS Code-style editor — free, fast, and 100% private.
JSON Parser
Run a real JSON parse in your browser — see exactly what your application will see, or exactly where it will fail.
JSON Validator
Strict RFC 8259 validation with the exact line and column of every error — plus one-click repair for broken JSON.
JSON Editor
A full VS Code-style editing experience for JSON — highlighting, error squiggles, undo/redo, search, and formatting in one place.
Converters
23CSV to JSON
Header-aware CSV parsing into clean JSON — pick the delimiter, keep IDs as strings or type them, and choose objects, arrays or JSON Lines.
JSON to CSV
Flatten JSON arrays into spreadsheet-ready CSV — nested keys become dot-path columns, quoting handled for you.
XML to JSON
Parse any XML document into clean JSON — repeated elements become arrays, attributes preserved, text nodes kept.
JSON to XML
Turn any JSON document into well-formed XML — element per key, repeated tags for arrays, declaration included.
XML Tools
9XML Formatter
Re-indent any XML document into clean, readable markup — comments and CDATA preserved, validation built in.
XML Parser
Run a real XML parse in your browser — see the structure parsers produce, or exactly where they fail.
XML Validator
Strict well-formedness checking with the exact line and column of every violation — fix XML errors in seconds.
XML Minify
Strip every insignificant byte from your XML — smaller payloads for SOAP calls, config files, and storage.
YAML Tools
5YAML Parser
See exactly what your tooling sees — full YAML 1.2 parsing with typed scalars, resolved anchors, and precise errors, shown as the JSON value it becomes.
YAML Validator
Full YAML 1.2 validation with the exact line and column of every error — catch the indent bug before your pipeline does.
YAML Formatter
Normalize any YAML to clean, consistent style — uniform indentation, canonical quoting, validation built in.
YAML Viewer
Explore any YAML document as an interactive tree — mappings, lists, and counts at a glance, anchors resolved.
HTML Tools
8HTML Formatter
Prettier-quality HTML formatting — embedded CSS and JavaScript formatted too, with a live preview one click away.
HTML Validator
Catch the unclosed <div> before it breaks your layout — structural validation with line numbers, instantly.
HTML Minify
Smaller pages, identical rendering — comments stripped and whitespace collapsed with pre/script/style protected.
HTML Viewer
Paste markup, see the page — sandboxed live preview beside prettier-formatted source.
CSS Tools
10CSS Formatter
One stylesheet workspace, three engines: prettier for canonical formatting, js-beautify for unminifying broken bundles, and a minifier for the compact form — pick the mode in the rail.
SCSS / Sass to CSS
The real dart-sass compiler in a browser tab — mixins, functions, @use and nesting evaluated, not approximated.
CSS Preprocessor Converter
One page for every cross-dialect trip — LESS, SCSS, indented Sass and Stylus, in any of the twelve directions.
Minify CSS
Strip every byte the browser doesn't need — comments gone, whitespace collapsed, savings shown.
Escape / Unescape
11SQL Escape
Three escaping styles for SQL string literals — ANSI quote doubling, MySQL backslashes, or LIKE-pattern wildcards — and back again.
JavaScript Escape
Make any text safe inside a JavaScript string literal — quotes, backslashes, newlines and control characters handled both ways.
.NET Escape
C#-ready string literals from any text — standard escapes plus \uXXXX Unicode, decoded back just as easily.
HTML Escape
Convert text to safe HTML entities and back — <, >, & and quotes handled, named and numeric entities decoded.
Encoding Tools
4URL Encode / Decode
Percent-encoding both ways — make any text safe in a URL, or turn %20-soup back into readable text.
JSON URL Encode
Put JSON in a URL safely — validated, percent-encoded, and decoded back to pretty-printed JSON.
XML URL Encode
Carry XML through URLs intact — well-formedness checked, percent-encoded, decoded back to formatted markup.
YAML URL Encode
YAML through URLs without corruption — validated, percent-encoded, and restored to clean formatting on decode.
Base64 Tools
4Base64 Encode Decode
Round-trip any text through Base64 — emoji and all — with a URL-safe mode for tokens and strict validation that catches corrupted input.
Base64 to JSON
Decode Base64 payloads straight to validated, pretty JSON — or encode JSON to Base64 for headers and env vars.
Base64 to XML
Decode Base64 payloads to validated, formatted XML — the SAML/SOAP debugging shortcut — or encode XML for transport.
Base64 to YAML
The Kubernetes-secret decoder — Base64 to clean, validated YAML and back, entirely in your browser.
Code Generators
25JSON to TypeScript
Paste a JSON or XML sample — the format is auto-detected — and get typed TypeScript models with names, nesting and nullability inferred for you.
JSON to Java
Paste a JSON or XML sample — the format is auto-detected — and get typed Java models with names, nesting and nullability inferred for you.
JSON to Python
Paste a JSON or XML sample — the format is auto-detected — and get typed Python models with names, nesting and nullability inferred for you.
JSON to Objective-C
Paste a JSON or XML sample — the format is auto-detected — and get typed Objective-C models with names, nesting and nullability inferred for you.
Formatters
19C# Formatter
Instant structural beautification for C# — paste any fragment, get readable indentation back.
Java Formatter
Fast structural beautification for Java — braces aligned, nesting indented, readable in one click.
SQL Formatter
Turn one-line query soup into clause-aligned, review-ready SQL — dialect-aware for MySQL, Postgres, T-SQL and SQLite.
JavaScript Formatter
The formatter your CI runs, in a browser tab — prettier-consistent JavaScript in one click.
Image Tools
27Image Compressor
Shrink JPG, PNG and WebP images in batches — pick a quality preset or a KB target, watch each file's exact savings, save what you like.
PNG to WebP
Shrink PNGs into modern WebP — transparency kept, size cut dramatically, all in your browser.
WebP to JPG
Turn .webp downloads into JPGs that open everywhere — batched, flattened onto white, converted on your own device.
PNG to JPG
Batch-convert PNG images to high-quality JPG right in your browser — drag, drop, convert, save. Nothing is ever uploaded.
Developer Tools
6JWT Decoder
Paste a token, read it like a human: decoded header and payload, annotated claims with local timestamps, expiry at a glance — plus optional signature verification.
Regex Tester
Type a pattern, watch matches light up in your text — with named capture groups, a replace preview, and flag toggles that behave exactly like JavaScript's RegExp.
Cron Expression Generator
Five dropdowns in, plain English out — with the next ten run times in your local timezone so you ship the schedule you actually meant.
UUID Generator
Random v4 or sortable, time-ordered v7 — generated in bulk with your browser's secure random source, formatted exactly how your codebase wants them.
Calculators
8EMI Calculator
Sliders for amount, rate and tenure — your EMI, total interest, and a full year-by-year amortization table update as you move them.
GST Calculator
Both directions of GST in one tool: add tax to a base price or pull the tax out of an inclusive price, with the CGST/SGST halves ready for your invoice.
SIP Calculator
Watch compounding do its work: future value, wealth gained, and a year-by-year growth table for any monthly investment plan.
Loan Calculator
Beyond the monthly payment: total interest, processing fees, and a payoff schedule that shows what the loan really costs over its life.
Text Tools
7String Utility
Sixteen everyday text operations in one tool — case conversion, line sorting and deduping, whitespace cleanup, counts.
Text Diff
Paste two versions, see what changed — matching lines aligned, insertions and deletions highlighted, nothing uploaded anywhere.
Markdown to HTML
Paste Markdown, get the HTML a Markdown renderer would produce — GitHub Flavored tables, task lists, fenced code and strikethrough included.
HTML to Markdown
Turn CMS exports, documentation pages and pasted markup into clean Markdown — wrappers and inline styling dropped, tables and code blocks kept.
Guides & tutorials
Understand the formats behind the tools
Written explanations with tested examples — the syntax rules, the errors that actually happen, and the fixes that actually work.
TOML vs YAML vs JSON: Choosing a Configuration Format
TOML, YAML and JSON compared for configuration files: comments, types, nesting, dates, tooling and the ecosystems that chose each — with a decision guide and conversions.
6 min read · 2026-09-18Guide · Developer ToolsHow to Escape a Single Quote in SQL
How to escape a single quote in SQL: the ANSI doubling rule, MySQL backslashes, Postgres dollar quoting, Oracle q-strings, LIKE patterns and binding.
9 min read · 2026-09-11Guide · Developer ToolsEscaping vs Parameterised Queries
Why escaping quotes does not stop SQL injection: numeric contexts, LIKE, identifiers, second-order attacks, and how prepared statements close the hole.
8 min read · 2026-09-11Guide · JSONJSON Minify vs Gzip: What Actually Shrinks a Payload
Measured bytes for three JSON documents raw, minified, gzipped and brotlied: what minification saves once compression is on, and when it still matters.
8 min read · 2026-09-11Tutorial · JSONHow to Validate JSON Against a Schema in Python and JavaScript
Validate JSON against a schema with Ajv in Node and jsonschema in Python: install, compile, read the error objects, and wire validation into CI.
9 min read · 2026-09-11Guide · Data FormatsYAML Multi-line Strings: | vs > vs Quoted (Indentation Rules)
How YAML literal | and folded > block scalars differ, what -, + and a digit change, when to quote instead, and why a run: block loses its line breaks.
9 min read · 2026-09-11