Otto
Writes code, runs it in an in-browser sandbox, and keeps iterating until the tests actually pass.
At a glance
Starts at
Free
The vendor's site is offline, so no current price was found.
Free tier
Yes
Platforms
Web
Best for
Developers prototyping quick, working code snippets
Not for
Teams needing a real backend or database environment
3.9 out of 5
Scored by a Toolio reviewer after real useOur verdict
Otto writes code and then actually executes and tests it inside a browser sandbox built on Web Containers, iterating on its own until the code runs without errors. There's no setup: it starts from a browser tab, installs npm packages, and edits its own TypeScript config as it works. Because everything runs in that in-memory, isolated environment, it's suited to prototyping and debugging self-contained snippets rather than testing against a real production database or backend.
✓What it does well
Self-testing iterationIt runs and tests its own code, iterating automatically until errors are fixed.
Zero setupEverything runs in the browser, so there's nothing to install locally to get started.
Real execution environmentIt can install npm packages and edit its own TypeScript config while working.
✕Where it falls short
Sandboxed onlyCode runs in an in-memory browser sandbox, not against a real backend or database.
No persistent environmentThe virtual file system is isolated, without a lasting local project setup carried between sessions.
Web onlyIt's browser-based only, with no desktop app or IDE plugin listed.
Key features
Autonomous code executionIt runs and tests the code it writes automatically.
Browser-based sandboxCode executes safely inside a Web Containers runtime with a virtual file system.
npm package supportIt can install and use npm packages as part of its work.
Embedded terminal and editorYou watch it run commands and edit code in an embedded terminal and editor.