YoSin Tools

CRC Checksum Calculator

Calculate cyclic redundancy check (CRC) values online. Supports CRC-32, CRC-16, CRC-8, CRC-64, and 100+ predefined models — plus fully custom polynomials. Input text, upload a file, or provide a URL.

Input
Output
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Frequently Asked Questions

What is CRC?
CRC (Cyclic Redundancy Check) is an error-detecting algorithm widely used in digital networks and storage to detect accidental changes to raw data. It works by treating the input as a polynomial and dividing it by a generator polynomial — the remainder is the CRC value.
What is the difference between CRC-8, CRC-16, and CRC-32?
The number indicates the bit width of the checksum. CRC-8 produces an 8-bit (1-byte) result, CRC-16 a 16-bit result, and CRC-32 a 32-bit result. Wider checksums detect a greater variety of errors but require more storage and computation.
What is CRC-32 used for?
CRC-32 is one of the most widely used checksum algorithms. It is used in Ethernet frames, ZIP files, PNG images, gzip compression, and many other formats to verify data integrity.
Can I use a custom CRC polynomial?
Yes. Select "Custom" from the Model dropdown to enter your own Width, Poly, Init, Xorout, Refin, and Refout parameters. This lets you implement any CRC variant, including proprietary ones.
Is my file uploaded to a server?
No. All processing is done entirely in your browser. Your file, text, or URL data is never sent to any external server. The calculation is performed using client-side JavaScript.

About the CRC Calculator

YoSin Tools provides a free, fast, and fully browser-based CRC calculator that supports more than 100 standardized CRC models along with a fully customizable polynomial engine. Whether you need to verify file integrity, debug embedded communications, or simply learn about cyclic redundancy checks, this tool has you covered.

Supported CRC Models

The tool supports all models defined in the CRC RevEng catalog, including the most popular variants:

  • CRC-32/ISO-HDLC — the standard CRC-32 used in ZIP, PNG, Ethernet, and gzip
  • CRC-32C (CRC-32/ISCSI) — used in iSCSI and newer protocols
  • CRC-16/MODBUS — widely used in industrial automation
  • CRC-8/DVB-S2 — used in satellite broadcasting standards
  • CRC-64/XZ — a 64-bit variant used in the XZ compression format

How to Use

Enter your text in the Input box, or switch the Input Type to File to upload a local file, or to URL to fetch a remote resource. Select your desired CRC model from the dropdown and the result appears instantly in the Output box. You can copy the result with one click or share it via the generated share link.

Custom Polynomials

For advanced users, the Custom model lets you specify every parameter of the CRC algorithm: the polynomial width (1–82 bits), the generator polynomial in hexadecimal, the initial register value, the final XOR value, and whether the input and output should be bit-reflected. This covers virtually every CRC algorithm ever defined.

Why CRC over MD5 or SHA?

CRC is designed for fast error detection in hardware and communication protocols, not for cryptographic security. It is much faster than MD5 or SHA-1 but is not suitable for security purposes because it can be intentionally forged. Use CRC when you need speed and simplicity; use SHA-256 or SHA-512 when you need collision resistance.