Tool Builder Developer
Write your own DuckyTools tool, watch it run, and download it as one self-contained HTML file.
Tool Builder is a free online tool that write your own DuckyTools tool, watch it run, and download it as one self-contained HTML file. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- Developer
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- None — it just works
- Works offline
- Yes, after the first visit
About Tool Builder
This runs the same contract every tool on this site is built from, and the same validator the build runs over all of them — so a definition that is valid here is one the real runtime will mount. Your code executes in an iframe with its own opaque origin, which is not decoration: definitions travel through the URL hash, so a share link is somebody else’s JavaScript arriving on our domain. The sandbox means it cannot read your storage, register a service worker, or make same-origin requests, and a shared definition is shown to you rather than run until you ask for it.
How to use it
- Everything tool builder needs is on this page.
- Your input is processed locally and discarded when you close the tab.
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
Questions
What can I actually build here?
The three pure kinds — text in and text out, text in and figures out, and form-style calculators. Those are the ones the runtime can render from a declaration alone. Tools that work on images, PDFs or files need the full runtime, so write those against the SDK and add them to the catalog rather than in this window.
Where is my work saved?
In this browser’s localStorage, on this device, as you type. It is never sent anywhere — there is no account and no server to send it to. Clearing site data loses it, so download or copy anything you want to keep.
Is the downloaded file really self-contained?
Yes. One HTML file with the tool, a small renderer and its styles inlined. No build step, no dependencies, no network requests at all. Open it from a disk, email it, or drop it on any static host.
Is it safe to open a share link somebody sent me?
The definition is displayed and not executed until you press the button, and even then it runs in a sandboxed frame with a separate origin. Read it first anyway — that is a reasonable habit for any code a stranger hands you.