Changelog – mtools

October 2026: Data Format Converter

New: Data Format Converter, for JSON, CSV, TSV, JSON Lines and form data, with query strings and whole URLs as input and Markdown tables as output. It warns whenever a conversion loses something, protects CSV against spreadsheet formulas, and converts files up to 50 MB in the background.
Text boxes with line numbers stay their normal height, however many lines you paste.
The privacy notice lists what the new tool can remember: its settings, never your data.

Search engines may now list mtools, with clearer page titles and descriptions, and a preview picture when a page is shared.
Every tool has a “Report it on GitHub” link under its result, which opens a short form on the mtools feedback page with the tool’s name filled in, and nothing you typed.
The contact page has separate email addresses for feedback, general questions and security reports, shown when you press a button so they are harder for spammers to collect.
The privacy notice explains what happens when you report something on GitHub.

Every text tool now shows its input and its result side by side on wider screens, with a status line under the result saying what happened.
Tool pages open with a short header; the full description is in the explanation below the tool.
Copy buttons show a tick and “Copied” for a moment after copying.
JSON Formatter: line numbers on the input and the result (never copied), Wrap long lines, and Expand result to give the result the full width. Both settings can be remembered.
Pages no longer move slightly while the colour and placeholder tools start up.

A new typeface, Atkinson Hyperlegible, chosen so that look-alike characters such as 0 and O, or 1, l and I, are easy to tell apart. It is served from mtools itself, like everything else. About the typeface
A new home page: search for a tool by name, format or keyword, then pick from a compact list.
Press / on any page to jump to the tool search.
Shorter names in the menu, and the theme picker shows a preview of each theme.
Slightly softer Light and Dark colours, with the same strong contrast.

New: Date and Time Converter, for Unix timestamps from seconds to nanoseconds, ISO 8601, email, HTTP and SQL dates, Excel, Windows and Apple epochs, and timezones, with daylight saving handled clearly.
A fifth menu category, Converters.
The privacy notice lists what the new tool can remember.

New: JSON Formatter and Validator, with JSONPath queries, search, the path at the cursor, syntax colouring, and files up to 100 MB.
New: Colour Picker and Converter, covering every CSS colour format, wide-gamut colours and gamut mapping.
New: Contrast Checker, with WCAG 2 checks and suggestions for passing colours.
New: Gradient Generator, with linear, radial and conic gradients, OKLab and OKLCH interpolation, and SVG and PNG export.
Code and data now appear in a fixed-width font throughout.
New pages: About, Privacy, Terms, Accessibility and Contact.
Server logs, which hold no IP addresses, are now deleted after 90 days.
Four low-glare themes (Soft cream, Soft blue, Soft green and Dim), and the theme setting moved to the bottom of the menu.
Tools are grouped into four categories: Encoders and Decoders, Generators, Colour Tools, and Formatters and Validators.
Fixed a brief flash when moving between pages in a dark theme.

Eight tools: URL Encode / Decode, HTML Entity Encode / Decode, Base64 Encode / Decode, JSON String Escaper, JWT Decoder, Hash and Checksum Generator, UUID / ULID Generator, and Placeholder Text Generator.
Everything runs in the browser, with no cookies, analytics or tracking.