Tools in this category
Turn Mermaid diagram code into a downloadable PNG, SVG, or JPG — live preview, all in your browser.
Encode or decode text to and from base64, with a URL-safe variant.
Compare two blocks of text and see added and removed lines side by side.
Sort lines alphabetically, numerically, or by length, and remove duplicates.
Collapse extra spaces, trim lines, and remove blank lines or line breaks.
Convert text between camelCase, snake_case, kebab-case, Title Case, and more.
Encode text to HTML entities or decode entities back to text.
Generate placeholder lorem ipsum text by paragraphs, sentences, or words.
Convert numbers between binary, octal, decimal, and hexadecimal.
Convert JSON arrays to CSV and CSV back to JSON, in your browser.
Test a regular expression against text and see matches and capture groups.
Convert colors between HEX, RGB, and HSL, and check WCAG contrast.
Translate a cron expression into plain English and a field-by-field breakdown.
Format, validate, and beautify JSON, in your browser.
Decode a JWT and inspect its header and payload, entirely in your browser.
Convert between Unix timestamps and human-readable dates.
Generate random UUIDs (v4), one or many, in your browser.
Percent-encode or decode URLs and query strings, in your browser.
Write Markdown and see a live HTML preview, in your browser.
Convert between YAML and JSON, both directions, in your browser.
Minify CSS, JavaScript, and HTML to shrink file size, in your browser.
Design CSS gradients visually and copy the code.
Design CSS box-shadows visually and copy the code.
Craft CSS border-radius shapes visually and copy the code.
Pick colors and get HEX, RGB, and HSL, including from an image.
Format, indent, and validate XML, in your browser.
Generate TypeScript types from JSON, in your browser.
Convert CSV data into a Markdown table, in your browser.
Calculate network, broadcast, and host ranges from an IP and CIDR.
Convert between px, rem, em, and pt for CSS.
Convert text to binary and back, in your browser.
Format and beautify SQL queries, in your browser.
Convert HTML into clean Markdown, in your browser.
Generate barcodes (Code 128, EAN, and more), in your browser.
About these tools
These developer tools are small, focused utilities for the chores that interrupt real work — formatting a messy payload, checking that a structure is valid, converting between formats, or generating a value you need. Every one runs in your browser, so there is nothing to install and the data you paste in stays on your machine.
The set spans the formats developers touch every day: a JSON formatter and validator, JSON to CSV and JSON to TypeScript converters, YAML to JSON, plus XML and SQL formatters. For encoding and decoding there are Base64, URL, and HTML-entity tools, a JWT decoder, a regex tester, a cron expression explainer, and number-base and Unix-timestamp converters. Text helpers like a diff viewer, a case converter, a Markdown previewer, and HTML to Markdown round out the workflow, alongside generators for UUIDs, lorem ipsum, and barcodes.
There are also front-end helpers — CSS gradient, box-shadow, border-radius and unit tools, a color converter and contrast checker, and an IP subnet calculator. Use them as quick, predictable utilities rather than a build pipeline: paste your input, get a clean result, and move on without an account or a download.
Frequently asked questions
No. The developer tools run client-side in your browser, so the JSON, tokens, or text you paste in are processed on your device and not uploaded to a server.
The decoder reads the token in your browser to show its contents; it does not send the token anywhere. It decodes the parts but does not verify the signature, so treat the output as a readable view, not proof a token is valid.
Formatting re-indents your input so it is readable, while validating checks that it follows the rules of the format and reports where it breaks. The JSON tool does both: it pretty-prints valid input and points out the error when input is malformed.
No. Every tool here works in the browser with no install, no account, and no download. Open the tool, paste or enter your data, and use the result right away.