I Built a Firefox Extension That Fills Any Form Instantly — No More Typing Test Data 🚀

Code A Program — Sun, 22 Mar 2026 17:57:17 +0000

Stop wasting time typing the same test inputs over and over again.

If you're a frontend dev or QA engineer, you know the pain. You're testing a signup flow for the 30th time today, and you're still manually typing John, Doe, john.doe@test.com, +1 555... into every single field.

I got tired of it. So I built FormSpackle.

⚡ What is FormSpackle?

FormSpackle is a Firefox extension that fills any form on any website with one click, using realistic, randomized data.

It's not just a basic autofill — it actually understands your form. It reads labels, placeholders, field types, and even works with modern UI component libraries.

🛠 What It Can Do

One-Click Fill

Click the extension icon, hit fill — done. The entire form is populated with realistic data in milliseconds.

Smart Field Detection

FormSpackle doesn't just blindly fill text boxes. It detects:

Input types (text, email, phone, password, URL, etc.)
Dropdowns, checkboxes, and radio buttons
Date and time pickers
Custom components from libraries like MUI, Ant Design, and more

Multi-Form Support

Got multiple forms on a page? You can choose to fill a specific form or all forms at once.

Fill Empty Only

Already filled in some fields? Use "Fill Empty Only" mode and FormSpackle will leave your existing data untouched.

Saved Profiles

Create and save your own data profiles — reuse them anytime across different projects or environments.

Built-in Field Inspector

Debug forms faster with the field inspector. Highlight detected fields and view what FormSpackle sees under the hood.

👨‍💻 Who Is It For?

Frontend developers testing forms during development
QA engineers running repetitive form validation tests
Power users filling job applications, registrations, or surveys quickly

🔒 Privacy First

No tracking. No external servers. No data leaves your browser.

Everything runs 100% locally. Your data stays yours.

💡 Real Workflows It Speeds Up

Testing signup & login flows repeatedly
QA regression testing on form-heavy apps
Filling job applications in bulk
Debugging form validation logic
Demoing forms to clients or stakeholders

🚀 Try It Out

FormSpackle is available on the Firefox Add-ons store:

👉 Install FormSpackle on Firefox

It's free, lightweight, and takes 10 seconds to install.

🗣 I'd Love Your Feedback

This is something I built to scratch my own itch as a developer. If you try it out, I'd love to hear:

What workflows do you use it for?
Any field types or edge cases it misses?
Features you'd like to see next?

Drop a comment below or reach out — every bit of feedback helps make it better. 🙏

Built with ❤️ for developers who fill forms way too many times a day.

DEV Community: Code A Program