About DevTools
A toolkit that works together
Most online tool sites are a drawer of disconnected boxes. DevTools is different: the tools pass their output to each other, a smart-paste box opens the right one for whatever you throw at it, and every editor is the real thing from VS Code — all running entirely in your browser, so nothing you paste or upload ever leaves your device.
What's different
Built around a few unusual ideas
Plenty of sites can format JSON or decode a token. These are the things you won't find together anywhere else.
A connected toolkit, not isolated widgets
Most online tool sites are one-off boxes. Here the tools hand their output to the next with a single click: decode a Base64 image and send it straight to the EXIF inspector, turn a JWT payload into a JSONPath query, or convert YAML to JSON and generate types from it — a real pipeline that never leaves your browser.
Smart paste figures out the tool for you
Paste anything — a JWT, an X.509 certificate, Base64, a Unix timestamp, a URL, even garbled mojibake — and the site recognizes what it is and opens the right tool with your input already loaded.
A real code editor, not a textarea
Wherever a tool works with code or data, its editor is Monaco — the same one that powers VS Code — so you get syntax highlighting, inline error markers that point at the exact line, code folding, multi-cursor editing, and find-and-replace instead of a plain textarea.
Insight, not just transformation
The tools go beyond converting text: they explain what a regex actually matches, decode and annotate a JWT’s claims, flag what an X.509 certificate is missing, and surface the details that usually take a second tool to find.
Principles
The ground rules
Private by architecture
Every tool runs entirely in your browser. There is no backend to receive your data — what you type, paste, or upload never leaves your device, so privacy is a property of how the site is built, not a promise.
Instant & offline
With no network round-trips, results appear as you type — and once a tool has loaded it keeps working without a connection, just as useful on a plane or a locked-down network.
Always free, no sign-up
No accounts, no paywalls, no usage limits — open a tool and start working. The site is supported by unobtrusive advertising so the tools stay free for everyone.
The toolkit
Available tools
43 tools and counting — new ones are added regularly.
ASN.1 Decoder
Decode ASN.1 DER/BER — paste PEM, Base64, or hex and see the tag–length–value tree behind X.509 certificates, keys, and CMS, entirely in your browser.
Barcode Generator
Generate 1D barcodes — CODE128, CODE39, EAN-13/8, UPC-A, ITF-14, MSI, Codabar and more — with live preview, colors, and PNG/SVG download, all in your browser.
Case Converter
Convert text between camelCase, PascalCase, snake_case, CONSTANT_CASE, kebab-case, Title Case, and more — all at once, in your browser.
Certificate Decoder
Decode X.509 / PEM certificates — view subject, issuer, validity, SANs, key, and fingerprints, all in your browser.
Code Formatter
Format and beautify JSON, YAML, TOML, XML, HTML, and CSS — with JSON/CSS minify and JSON schema validation.
Code to UML
Turn TypeScript or Java source into a Mermaid class diagram — classes, interfaces, enums, fields, methods, inheritance, and interfaces — rendered live in your browser.
Color Converter
Convert colors between HEX, RGB, HSL, HSV, and OKLCH, with a picker, alpha, and a WCAG contrast checker — all in your browser.
CSS Unit Converter
Convert between CSS units — px, rem, em, pt, vw, vh, and more — with live visual feedback and a full conversion table.
Data Diff
Compare two JSON, YAML, or TOML documents by structure, not text: added, removed, and changed values with their paths. Key order and formatting are ignored. Runs in your browser.
Diff Viewer
Compare two texts or code snippets side by side with line-level difference highlighting.
Encoder / Decoder
Encode and decode text with Base64, URL, and Hex — UTF-8 safe, instant, and fully in your browser.
HAR Viewer
Open a .har network export and explore its requests, sizes, status codes, and a timing waterfall — entirely in your browser. Nothing is uploaded.
Hash Generator
Compute MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes of text or a file, plus HMAC — all at once, entirely in your browser.
HEIC to JPG Converter
Convert iPhone HEIC/HEIF photos to JPG, PNG, or WebP — fast, multi-threaded batch conversion entirely in your browser. Nothing is uploaded, and location and metadata are removed by default.
Image Compressor
Fast, multi-threaded image compression — shrink many images at once by quality or to a target file size, with WebP/JPEG output and optional resizing, entirely in your browser.
Image Converter
Convert, resize, and compress images between PNG, JPEG, and WebP, or copy them as a Base64 data URI — entirely in your browser.
Image to Text (OCR)
Extract the text from a screenshot, photo, or scanned document with OCR — in 18 languages, entirely in your browser. Nothing is uploaded.
JSON ↔ YAML ↔ TOML
Convert structured data between JSON, YAML, and TOML, live in your browser.
JSON to SQL
Infer a SQL CREATE TABLE from a JSON sample or a JSON Schema — column types, nullability, and a primary-key guess — for PostgreSQL, MySQL, or SQLite. Runs in your browser.
JSON to Types
Turn a JSON sample or a JSON Schema into TypeScript, Zod, Go structs, Python dataclasses, Kotlin data classes, or Java records/Lombok. Infers optional and nullable fields. Runs in your browser.
JSONPath Tester
Query JSON live with JSONPath — filter, slice, and recurse, and see each matched value with its path, all in your browser.
JWT Debugger
Decode and inspect JSON Web Tokens: view the header and payload, check expiry, and verify HS/RS/PS/ES signatures — all in your browser.
JWT Signer
Build a JWT header and payload and sign it with HMAC (HS256/384/512) or an RSA/ECDSA private key (RS/PS/ES) — entirely in your browser. Nothing is uploaded.
Log & Trace Analyzer
Open a huge log file — JSON/NDJSON, logfmt, syslog, or Java/app-server text — and get instant time-range narrowing, faceting, a timeline, request tracing, and full-text search, entirely in your browser with nothing uploaded.
Markdown Editor
Write Markdown with a live GitHub-flavored preview, a table of contents, and one-click export to Markdown or HTML — entirely in your browser, nothing uploaded.
Metadata Inspector
Inspect the hidden metadata in a photo or document — EXIF, GPS location, author, dates, and more — right in your browser. Download a cleaned copy with the metadata removed.
Metadata Stripper
Strip EXIF, GPS, author, and hidden metadata from images and documents in one batch — locally in your browser. JPEG, PNG, WebP, GIF, PDF, Office, OpenDocument & EPUB.
Mock Data Generator
Generate realistic fake test data — names, emails, dates, and more — as JSON, CSV, SQL, or XML, from a schema you build or import.
Mojibake Fixer
Repair garbled text where UTF-8 was misread as Windows-1252 — turn “café” back into “café” and “’” back into “’”. Runs entirely in your browser.
OpenAPI Code Generator
Turn an OpenAPI 3.x spec (JSON or YAML) into a typed TypeScript fetch client, or into models for Go, Python, Kotlin, Java, and Zod. Runs entirely in your browser.
Password Hash Generator
Hash a password with Argon2id, bcrypt, scrypt, or PBKDF2 — with OWASP-recommended parameters — and verify a password against a hash, entirely in your browser.
PDF Redactor
Redact a PDF so the text is permanently removed, not just covered — and strip its hidden metadata, comments, and attachments. Entirely in your browser, nothing uploaded.
PDF Toolkit
Merge, split, reorder, rotate, and delete PDF pages, turn images into a PDF, or export pages as images — entirely in your browser, nothing uploaded.
QR Code Generator
Generate QR codes for URLs, Wi-Fi, vCards, events, email, SMS, geo, phone, and text — with selectable error correction, and PNG/SVG download.
QR Code Reader
Decode a QR code from an image or your camera, entirely in your browser. Reads URLs, Wi-Fi, contacts, and more — nothing is uploaded.
Regex Railroad Diagram
Visualize a regular expression as a railroad diagram and read a plain-English, step-by-step explanation. Hover to link the two. Runs in your browser.
Regex Sample Generator
Generate example strings that match a regular expression, then send them straight into the Regex Tester. Every sample is verified to match — all in your browser.
Regex Tester
Build and test regular expressions live — highlight matches, inspect capture groups, and preview replacements.
Timestamp Converter
Convert between Unix epoch time and human-readable dates — seconds, milliseconds, ISO 8601, UTC, time zones, and relative time.
UML to Code
Turn a Mermaid class diagram into TypeScript, Python, Java, or C# code — classes, interfaces, enums, inheritance, and relationships — live in your browser.
URL Inspector
Break a URL into its parts and an editable query-string table, then rebuild it. Decodes parameters and exports them as JSON. Runs in your browser.
Workflow Builder
Chain multiple tools into a pipeline and run it in one place: decode, convert, format, and generate types in sequence. Runs entirely in your browser.
XPath Tester
Test XPath expressions against XML or HTML live — see matched nodes, their location paths, and string/number/boolean results, all in your browser.
Under the hood
Why browser-only?
Most online developer tools send your input to a server to process it. That means your tokens, payloads, and config files leave your machine. DevTools takes the opposite approach: every transformation runs locally in JavaScript, so sensitive data never travels anywhere. It also makes the tools faster, since there is no network latency, and it keeps the service inexpensive to operate.
We focus on doing a few things well: fast, accurate tools with a clean, distraction-free interface that works equally in light and dark mode. Each tool is built to handle real edge cases — UTF-8 and binary data, large inputs, malformed content — and to fail with clear, helpful messages rather than silently producing wrong output. The codebase is modular, so new tools can be added quickly without affecting the ones you already rely on.
Questions
Frequently asked questions
How is this different from other online developer tools?+
Three things. The tools are connected — most sites give you isolated boxes, whereas here each tool can hand its output to the next (decode a Base64 image and inspect its EXIF, turn a JWT into a JSONPath query, convert YAML to JSON and generate types). A smart-paste box detects what you paste and opens the right tool automatically. And wherever you are editing code or data, the editor is Monaco — the one behind VS Code — instead of a plain textarea. All of it runs entirely in your browser.
Is DevTools really free?+
Yes. Every tool is completely free to use with no account, sign-up, or usage limit. The site is funded by unobtrusive advertising.
Is my data safe?+
Yes. All processing happens locally in your browser using client-side JavaScript. The data you paste or upload is never transmitted to or stored on any server — there is no backend that receives it.
Do I need to create an account?+
No. There is nothing to sign up for. Just open a tool and start using it.
Can I use the tools offline?+
Mostly, yes. Once a tool has loaded, it runs entirely on your device, so it continues to work without a connection.
Why are the tools browser-only?+
Keeping everything client-side means your data stays private, the tools respond instantly, and the service is cheap to run — which is what lets us offer it for free.
Can I suggest a new tool?+
Absolutely — many tools started as user requests. Head to the Contact page and send your idea our way.
Ready to get started?
Pick a tool and start working — no setup, no sign-up, nothing to install.