CRC Calculator
CRC Calculator
Premium CRC presets + custom model. Fast, deterministic, and designed for large files — fully in your browser.
Your data stays in your browser. No uploads.
Preset
Check value “123456789”: 0xCBF43926 (0xCBF43926)
Input
Show steps
Output
Processed: 0 bytes
No output yet. Calculate to see results.
Advanced
Custom CRC model
Preset parameters are active. Enable custom model only if you need to match a specific implementation.
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CRC (Cyclic Redundancy Check) is a fast checksum used to detect accidental changes in data. It’s common in network protocols, file formats, embedded systems, and storage pipelines. This CRC calculator lets you compute checksums for text (UTF‑8/ASCII), raw hex, uploaded binary files, Base64, or Data URIs — with no uploads and no server processing. Choose a preset like CRC‑32 (IEEE), CRC‑32C, CRC‑16/MODBUS, or CRC‑8, or switch to the custom model builder to match the exact width, polynomial, init, reflection, and xorOut used by your system. For large inputs (50MB+), calculations run in a Web Worker with chunked reads to keep the UI responsive. Use the “Expected CRC” field to verify results and the small “Show steps” mode to debug byte-by-byte CRC evolution on tiny inputs.
FAQ
Is CRC encryption?
No. CRC is a checksum for error detection; it does not hide or protect data.
Which input formats are supported?
Text (UTF‑8/ASCII), hex, file uploads, Base64, and Data URIs.
What is the difference between CRC‑32 and CRC‑32C?
They use different polynomials. CRC‑32C (Castagnoli) is common in iSCSI, SSE4.2 instructions, and storage systems.
Why doesn’t my CRC match?
Most mismatches come from different init/xorOut, RefIn/RefOut, endianness, or using a different polynomial/preset.
Do you upload my file?
No. Everything runs locally in your browser.
Can it handle large files?
Yes. File mode uses a Web Worker and chunked reads to stay responsive for 50MB+ files.
What does “Expected CRC” do?
It compares your expected value with the computed CRC and shows Match/No match.
Does it support Data URIs?
Yes. data:<mime>;base64,... inputs are parsed and decoded before CRC is calculated.
What does “Show steps” show?
For small inputs, it shows the CRC value after each byte for debugging.
Is the result deterministic?
Yes. No AI and no server calls; the same input and model always produces the same CRC.