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Format, decode, convert and test everything you paste. One offline app, for you and your coding agent.

OffPaste is a desktop app that formats JSON, decodes JWTs, tests regex and converts Base64, URLs and timestamps. Each tool runs on your machine. In 0.2, your coding agent gets the same tools through the offpaste CLI and MCP.

Coming soonOffPaste 0.1 for macOS and Linux, with Windows as an unsigned beta.Free. No account.

The tools make no network calls. Code: GPL-3.0-or-later, public at 0.1.

Why OffPaste

  • Offline and private

    Paste a JWT and read its claims with the Wi-Fi off. What you paste stays in memory. It reaches the disk only if you save it as a snippet.

    The tools make no network calls. The app talks only to offpaste.com: an update check that you can turn off, plus analytics and crash reports only if you say yes. None of them holds your input.

  • For you and your coding agentIn 0.2

    The offpaste CLI comes with the app and gives your coding agent the same tools over MCP.

    The app, the CLI and the MCP server run the same Rust code, so your agent gets the same output that you see.

  • Every tool, one keystroke

    Press ⌘K (Ctrl+K), type “jwt”, press Enter and paste. ⇧⌘C (Shift+Ctrl+C) copies the output.

    12 tools in 0.1, and ⌘K (Ctrl+K) finds each one by name or description.

Paste it and read the result.

12 tools in 0.1

  • JSON

    Format and validate JSON, and read it as a tree.

  • JWT decode

    Split a token into its header, payload and signature, and read the claims.

  • Base64

    Encode and decode Base64, for text and for images.

  • URL

    Encode and decode text for a URL, and split a URL into its parts.

  • Unix timestamps

    Change a Unix timestamp to a date, and a date to a timestamp.

  • UUID and ULID

    Make new UUIDs and ULIDs.

  • Hashes

    Calculate the hash of the text that you paste.

  • Regex tester

    Test a pattern on your text, with a color for each group and a replacement preview.

  • YAML and JSON

    Change YAML to JSON, and JSON to YAML.

  • Text diff

    Compare two texts and see what changed.

  • Number bases

    Change a number between decimal, hexadecimal, octal and binary.

  • Color converter

    Change a color from one format to another, for example from hex to RGB.

FAQ

“A website is quicker. Why install an app?”
OffPaste is one keystroke away too: ⌘K (Ctrl+K), type, paste. Each tool runs as native Rust code on your machine, not in a browser tab, and makes no network calls. An app also does what a website cannot. From 0.2, your coding agent runs the same tools through the offpaste CLI and MCP. And anyone can read the code from 0.1.
“My input is never clean.”
Smart quotes, stray whitespace, a data: prefix, a JavaScript object in place of JSON: each tool cleans it up and tells you what it changed.
“Free now, paid later?”
It is free, with no account. The code is GPL-3.0-or-later and becomes public at 0.1, so anyone can build it from source.
“Offline? It still phones home, right?”
The app makes three calls, all to offpaste.com. The update check is on, has no ID and has one toggle to turn it off. Analytics and crash reports are off until you say yes. None of them holds what you paste.
When can I download it?
There is no date yet. Version 0.1 comes first for macOS and Linux, with Windows as an unsigned beta. This page changes to download buttons on release day.
Does it run on Windows?
Yes, as an unsigned beta in 0.1. Windows can show a warning before the first start.
Can my coding agent use it?In 0.2
Yes, from 0.2. The offpaste CLI serves the tools over MCP, on stdio. It makes no network calls, and it never overwrites your original files.
What does the regex tester do?
It matches as you type and gives each group its own color, in the pattern and in the text. It has flags per expression, a replacement preview, commented multiline patterns, and JavaScript or Rust syntax.

One offline app for everything you paste while you code. From 0.2, for your coding agent too.

Coming soonOffPaste 0.1 for macOS and Linux, with Windows as an unsigned beta.Free. No account.

A note from the maker

A request fails. You copy the JWT from it and want to see the claims. The quickest place is a website, so you paste it there.

That token was not yours to share. Neither was the API payload you formatted on the next tab, or the config you diffed after that.

I have done this too. So I am building OffPaste: the tools I reach for every week, in one desktop app that keeps what I paste on my machine.

Version 0.1 has 12 tools, each one a keystroke away, with no account and no tool that touches the network. I build it for my own daily work first.

Julio Márquez, maker of OffPaste