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Validate NFe Key

Validate the 44-digit access key of Brazilian NFe/NFCe with Modulo 11 check digit. Decodes state, date, CNPJ, model and series. Instant result.

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44 numeric digits (spaces accepted)

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Validate NFe Access Key Online

Online NFe Access Key Validator - Free and Instant

Our free online nfe access key validator performs instant validation using the official algorithm. Simply enter the number, click the button, and get an immediate result indicating whether the document number is valid or invalid. The validation checks digit verification, format correctness, and known invalid patterns to ensure accuracy.

Key Features

  • Instant validation using the official algorithm published by the Brazilian government
  • Support for both formatted and unformatted input
  • Detection of known invalid sequences and repeated digit patterns
  • Complete privacy with all processing done in your browser
  • Mobile-friendly responsive interface that works on any device
  • No registration or API key required for unlimited use

The validation algorithm follows the official specification published by the Brazilian government. The tool checks not only the mathematical validity of the check digits but also rejects commonly used test numbers and sequences of repeated digits that, while mathematically valid, are not real document numbers in use.

This tool runs entirely in your browser using JavaScript and no data is transmitted to any server, ensuring complete privacy and security for sensitive document numbers. It works offline once the page is loaded and provides instant feedback as you type your input.

Whether you are a developer testing form validation logic, an accountant verifying client documents, or simply need to check a number quickly, this free tool saves time and eliminates manual calculation errors. Combine it with our generator tools for comprehensive testing workflows.

Frequently Asked Questions

What is an NFe access key?
The access key is a 44-digit code that uniquely identifies a Brazilian Electronic Invoice (NFe). It contains the state code (UF), date, issuer CNPJ, model, series, invoice number, emission type, numeric code, and check digit.
How does the check digit validation work?
The check digit (44th digit) is calculated using Modulo 11: each of the first 43 digits is multiplied by cyclic weights from 2 to 9, the results are summed, divided by 11 to get the remainder. If the remainder is 0 or 1, the check digit is 0; otherwise, it is 11 minus the remainder.
Does this tool query SEFAZ?
No. This tool performs mathematical validation only (check digit + structural format). It does not access the SEFAZ (State Tax Authority) portal and cannot confirm whether the invoice actually exists or its authorization status. For generating test NFe keys, use our NFe Key Generator.