Fill forms with valid test data: names, addresses, phones, test cards, national IDs, edge cases. One field or the whole form.
Users
8
store count
Rating
5.0 / 5
unchanged in 30 days
Ratings
2
total ratings
Store rank
#208K
#174K among extensions
Version
0.8.0
updated 14 Oct 2026
About Data Tinker: Test Data Generator & Form Filler
Data Tinker gives you valid test data while you test a form: identifiers that
pass the same checks a real one does, in a side panel next to the page. Drag a
value into a field, or fill in the whole form with one click.
Everything is generated in your browser. There is no account, no server and
nothing leaves your machine.
DATA THAT PASSES VALIDATION
Every generator computes the check digit or the format the real thing has, and
the tests run against examples published by the issuing bodies — not against
the generator agreeing with itself.
• Identity documents, tax numbers and bank accounts from Germany, Portugal,
Spain, the United Kingdom and the United States, plus VAT numbers from across
Europe.
• Everyday form data: test card numbers, phone numbers, emails, addresses,
dates and passwords, product barcodes and book numbers, and technical values
for developers.
• Whole profiles — a person, with age, job title and salary, or a company —
where the city, the region and the postal code belong together. Pick the country once, and the form fill, your
rules and the right-click menu follow it.
• Many at once: a table of up to 10,000 profiles with the columns you choose —
an ID counter, or one built from the others, like an email from the name —
as CSV, JSON or SQL INSERT statements. Or "All in one": a value from every
generator on a single screen.
Test data that is safe to use: cards are the test numbers payment gateways
publish for exactly this, and no bank issues; phone numbers come, where the
country has one, from the range its regulator reserves for fiction.
FILL IN THE WHOLE FORM
• One button, a right-click or Alt+Shift+D. Data Tinker recognizes each field
by its autocomplete hint, its name, its label and its type — and when nothing
else says what it wants, by the format it asks for — and types into it the
way a person does, so React forms and masked date fields keep the value.
• Time, week, month, color and range fields too, within their limits. If you
build the form, a data-tinker attribute says what a field is, or that it is
off limits.
• It leaves alone what you cannot see — the hidden fields that catch bots.
• Then it shows a report: what went into each field, which ones need a look,
and which required ones got nothing. Copy it into a ticket as a table, or as
JSON.
• A small icon next to the focused field fills it with one click (with Shift,
the whole form). You can switch it off, or limit it to some sites.
MAKE IT YOURS
• Rules: "if the field mentions these words, put this in it" — a generator, a
fixed value, a number of N digits, a date between two years, one of a list, or
a pattern like ###-@@@ for your own reference numbers.
• Templates: detect a form's fields, or capture the values it has right now,
and paste them into another form — also inside an iframe. A template can hold
several data sets (an individual, a company) and fill a page on its own as
soon as it opens, and three of them can have a keyboard shortcut.
• Projects: group your rules and templates by application, each with the sites
it belongs to.
• Back up everything to a file and restore it in another browser. Templates that
arrive from a file never fill a page on their own until you switch that on.
FIND THE EDGES
• Boundary values with the reason each one is there: very long text, Unicode
that breaks counters, injection strings, extreme numbers, odd emails and dates.
• "Test the form's limits" tries them field by field and tells you what the form
accepted, what it cut and what it rejected — including the limits a page only
states in its error messages.
PRIVACY
Data Tinker asks for access to all sites so it can fill a form on whichever page
you are testing, and show its icon there. It reads a page's form only when you
ask it to — fill, detect, capture or test the limits — and only in your browser.
Password fields are never captured. What you create is stored locally and never
sent anywhere.
Interface in English (US and UK), German, Portuguese and Spanish.