What Is a Tax ID Generator?
The Tax ID Generator is a developer and QA utility that creates randomly generated, mathematically valid identification numbers for software testing. When you build registration forms, payment flows, or databases that accept national tax identifiers, you need realistic sample data to verify that your validation logic and formatting masks work correctly — but using real people's numbers is both unethical and a violation of privacy laws such as the GDPR and Brazil's LGPD. This tool solves that problem by producing numbers with correct check digits that pass format validation yet belong to no real person or company. It supports the main tax identifiers across the languages our site serves: CPF and CNPJ for Brazil, DNI and NIE for Spain, CUIT/CUIL for Argentina, and SSN and EIN for the United States.
A tax ID generator creates identification numbers — such as Brazilian CPF and CNPJ, US SSN and EIN, Spanish DNI and NIE, and others — that are structurally valid but entirely fictitious. "Structurally valid" means each number has the correct length and a check digit that passes the official validation formula, so a form will accept it; "fictitious" means it is randomly generated and does not belong to any real person or company. It exists purely so developers and testers have safe sample data.
How to Use the Tax ID Generator
- Select the document type you need from the dropdown — each option is labelled with its country so you can quickly find CPF, CNPJ, DNI, NIE, CUIT, SSN, or EIN.
- Set how many numbers you want to generate (up to 50 at once) and choose whether to include standard formatting such as dots and dashes, which is useful for testing input masks.
- Click Generate and copy any individual result with its copy button, or use Copy All to grab the entire batch at once for pasting into your test suite or spreadsheet.
Use Cases: Who Needs a Tax ID Generator?
- Developers building and testing registration, billing or KYC forms that validate a national tax number.
- QA engineers filling test databases and end-to-end test cases with realistic identifiers.
- Teams demoing software or recording tutorials without exposing a real customer’s document.
- Anyone verifying that a validation routine accepts well-formed IDs and rejects malformed ones.
The Logic Behind the Numbers
Each document type has a fixed format and a check-digit algorithm. The generator first draws the random base digits, then runs the official calculation — for example the modulo-11 weighting used by Brazil’s CPF and CNPJ, or the Luhn-style and modulo checks used by other countries — to compute the trailing check digits that make the whole number valid. The result therefore passes the same validators a real submission would.
Because only the format and check digits are real, the numbers carry no identity: they are not drawn from any registry and are extremely unlikely to coincide with an issued document. They are intended strictly for software development and testing — never to impersonate a person or commit fraud.
Benefits and Use Cases
- Lets developers and QA engineers test forms, APIs, and validation rules with data that passes real check-digit algorithms, catching bugs that random strings would miss.
- Protects privacy and keeps you compliant with data-protection laws by eliminating any need to use real personal tax numbers in development or staging environments.
- Covers multiple countries in a single tool and runs entirely in your browser, so your generated data is never sent to or stored on any server.
Privacy First: Why Use Fastway Tools?
Every number is generated locally in your browser with client-side JavaScript. Nothing is requested from or sent to our servers, and no list of generated IDs is stored anywhere. That keeps your test workflow private and instant, and the tool keeps working offline once the page has loaded.