About

This tool generates and validates NB (Número do Benefício) numbers, which are unique 10-digit identifiers assigned by the Brazilian Social Security Institute (INSS) to beneficiaries. This utility is essential for developers and QA engineers who need to test software compliance with Brazilian government standards without using real, sensitive data.

The generator uses the standard Modulo 11 algorithm to ensure mathematical validity. While these numbers satisfy the checksum logic required by form validators and banking systems, they are randomly generated and do not correspond to actual active benefits. Using this tool eliminates the risk of using real private data during the development lifecycle.

Formulas

The verification digit D for an INSS NB is calculated using the Modulo 11 algorithm. The process iterates through the first 9 digits.

S = 9∑i=1 (d_i × w_i)

Where d_i is the digit at position i (from right to left) and w_i is the weight, cycling from 2 to 9.

R = S % 11

D =

{

0 if 11 − R ≥ 1011 − R otherwise

Reference Data

Document	Format Mask	Length (Digits)	Check Digits
NB (INSS)	999.999.999-9	10	1
CPF	999.999.999-99	11	2
CNPJ	99.999.999/0001-99	14	2
PIS/PASEP	999.99999.99-9	11	1
CNS (Health)	999 9999 9999 9999	15	Algorithmic
Título Eleitor	9999.9999.9999	12	2

Frequently Asked Questions

No. These numbers are mathematically valid but strictly artificial. They do not exist in the official INSS database. Attempting to use them for fraudulent purposes or to claim benefits is illegal and will be rejected by official government systems.

The NB consists of 10 digits. The first 9 are the base number, and the 10th is a check digit. The algorithm sums the multiplication of the first 9 digits by weights ranging from 2 to 9. The remainder of this sum divided by 11 determines the check digit.

Yes. This tool is built with client-side JavaScript. Once the page is loaded, you can disconnect from the internet and generate as many numbers as needed. No data is ever sent to a server.

In the Modulo 11 standard used by the INSS, if the result of (11 - remainder) equals 10 or 11, the check digit automatically becomes 0.