Fake Filler or FormCarbon?
Fake Filler fills every field on a page with made-up data, and many developers use it to test forms. FormCarbon fills forms from a profile you save, and its developer mode adds generated test data. This page starts with the cases where Fake Filler is the better choice.
FormCarbon is made by Quillfold, which publishes this page.
When Fake Filler is the better fit
You want generated test data at no cost
Fake Filler’s free Lite plan fills forms with made-up data. In FormCarbon, test data comes from developer mode, which is part of Pro: every Pro feature is free for 14 days after you install, and after that developer mode needs Pro.
You want one key to fill everything
In Fake Filler’s public source code, Ctrl+Shift+F fills every field on the page, and separate commands fill one form or one field. FormCarbon shows a preview first and writes when you press Fill.
You use Edge or Firefox, or want settings to sync
Fake Filler is offered for Chrome, Edge and Firefox, and its settings sync across the browsers where it is installed. FormCarbon is in the Chrome Web Store and keeps its data on this device only; you move it with a backup file.
You want a long track record
Fake Filler has 400,000 users in the Chrome Web Store. FormCarbon is new: it has been in the store since October 2026.
When FormCarbon is the better fit
You want to see each value before it is written
FormCarbon lists every field and the value it will get. You can change a row or leave it empty, and Undo puts the fields back as they were. We did not find a preview or undo in Fake Filler’s listing or on its website.
You fill forms with your own details too
The same extension fills from profiles you save (two on the free plan, with unlimited fills), and in developer mode from generated test data. You do not need a second tool for real sign-ups.
Your test data has to match the form’s country
Developer mode makes names, addresses, phone numbers, companies and dates of birth for the region you choose. The fill engine is checked against 53 sample forms in 9 languages (1,010 fields), with postal codes and phone numbers split across several boxes and Japanese furigana. The forms are public, so you can try them. More: the sample forms
You need the same data again, or a new address each run
A fixed seed fills the same data every time. A run number and an email alias (your own address with a +tag) give each run its own address; without an alias, addresses use domains reserved for testing, such as example.com.
Some fields must stay as they are
FormCarbon does not fill hidden fields, including honeypots that catch bots. It does not tick consent or newsletter boxes by default, and never submits the form. A throwaway test password and card numbers that payment providers publish for testing go in only when you pick them in the preview, and are never saved.
You would rather not give access to every site
FormCarbon reads only the tab where you press its button or shortcut. The Pro feature that fills a site when you open it asks for that one site. Fake Filler’s public source code (version 3.4.0) loads its script on every website; we did not check the permissions of the store version, 4.1.0.
Side by side
| Fake Filler | FormCarbon | |
|---|---|---|
| Pricing model | Free Lite plan; Pro is a monthly or yearly subscription | Free plan; Pro by monthly or yearly subscription or a one-time purchase |
| Generated test data on the free plan | Yes | No: developer mode is Pro (free for the first 14 days) |
| Profiles | Yes, with custom fields per URL | Profiles of your own details: 2 free, unlimited with Pro |
| Preview before filling | Not listed | Yes |
| Undo | Not listed | Yes |
| Hidden fields | Skipped | Skipped, including honeypots |
| Test data for a chosen region, fixed seed, email alias | Not listed | Yes (Pro) |
| Keyboard shortcut | Yes (Ctrl+Shift+F in the public source) | Yes |
| Browsers | Chrome, Edge, Firefox | Chrome |
| Settings sync | Yes, across browsers | No: stored on this device; backup to a file |
| Site access | Every website in the public source (3.4.0); store version not checked | The tab you click; one site at a time for fill on open (Pro) |
| Interface languages | English (store listing) | English, Japanese, German, French, Spanish, Portuguese, Chinese (Simplified and Traditional), Korean |
| In the Chrome Web Store | 400,000 users; last updated 3 August 2024 (4.1.0) | New (October 2026) |
“Not listed” means we did not find it in the product’s store listing, website or public source on the date above. “Not checked” means we did not look into it. Either may still work. We have not run Fake Filler on our sample forms. Fake Filler is a trademark of its owner. Quillfold is not affiliated with it.
Using both
They work side by side. Both suggest Ctrl+Shift+F as their shortcut, so if you install both, set one of them to another key in chrome://extensions/shortcuts. Keep Fake Filler for quick fills in a development build, and open FormCarbon when you need to check each value, fill from your own details, or fill forms from another country.