← Back to projects
Developer tools
DevFiller
Testing a form means typing the same fake name, email and address again and again — and generic autofill guesses from the field name alone, ignores validation rules, and breaks on French or Arabic forms.
Browser extensionTest dataQA toolingChrome, Edge & Firefox
The result
93.5% of real-world fields filled correctly, in one click.
- The problem
- Testing a form means typing the same fake name, email and address again and again — and generic autofill guesses from the field name alone, ignores validation rules, and breaks on French or Arabic forms.
- What I built
- A browser extension that reads every field before filling it, generates one consistent fictional identity that passes each field's rules, and shows its reasoning in a side panel with an undo.
- The result
- One click fills a real-world form correctly 93.5% of the time, on Chrome, Edge and Firefox, with nothing leaving the browser.
The problem
Testing a sign-up flow means typing the same name, email and address dozens of times a day. Generic autofill tools guess from the field name alone, so they put a phone number in a postcode box, ignore the field's own validation rules, and give up on forms written in French or Arabic.
Reading the form before filling it
Each field is scored on all the evidence it carries — its label, name, placeholder, autocomplete hint, units and, for a select, its options — and the form is read as a whole, so a confirmation field repeats the password and an end date lands after the start date. When the rules are unsure, a small model that ships inside the extension suggests a type, entirely offline.
The values are generated to pass: they respect each field's length and pattern, belong to one consistent person, and fill ARIA widgets and rich-text editors as well as plain inputs.
- 46 field types, recognised from labels in English, French and Arabic.
- A side panel (Alt+Shift+F) showing each field's type, confidence and evidence — with an undo for the last fill.
- Addresses and phone numbers from the US, France or Algeria, including all 69 wilayas.
- Sandbox test cards only, and obvious test values for anything sensitive.
- Custom values, excluded fields, a seed for repeatable data, and export of a form as a test fixture.
Private by design
There is no DevFiller server. Settings stay in the browser's local storage and the extension never submits a form. The optional AI suggestions use your own Groq or Gemini key and send only descriptions of the fields — never the values on the page.
The result
On about 500 real-world forms — 2,500 hand-labelled fields — DevFiller fills 93.5% of fields with a value that fits and gets 1.9% wrong. A thousand fields are classified in about 70 ms. It is published on the Chrome Web Store, Firefox Add-ons and Microsoft Edge Add-ons.
Your project starts with one message
First call is free, 20 minutes
Write what is eating your time or losing you money. I reply within one working day with a plan and a price — and if I am not the right person, I will say so.
- 01
- You send the message; I reply within a working day with a few questions.
- 02
- A 20-minute call to understand what you actually need.
- 03
- A written plan with a clear price and timeline, no commitment.
Tell me what you need
Questions about Haithem? Ask the assistant.