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WebSocket Frame Explainer

Decode WebSocket frame bytes into opcode, flags, mask and payload.

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WebSocket frame (hex bytes)

Paste raw frame bytes as hex (spaces/colons/0x ignored) — e.g. captured from a packet dump.

Decoded frame

FIN
1 (final)
Opcode
1 (Text)
Masked
Yes (client→server)
Payload length
5 bytes
Header bytes
6
Total frame size
11

Mask key: 37 fa 21 3d

Decoded text payload
Hejlo

About the WebSocket Frame Explainer

Paste hex bytes from a WebSocket frame to decode the FIN bit, opcode, mask flag, payload length and unmasked payload, with each field explained.

Examples

Example

81 05 48 65 6c 6c 6f

Output

Text frame, FIN=1, payload: Hello

Keyboard shortcuts

  • Copy the main outputCtrl / ⌘ + Shift + C
  • Download the resultCtrl / ⌘ + S
  • Share this toolCtrl / ⌘ + Shift + S
  • Reset the inputsAlt + R
  • Open the tool search paletteCtrl / ⌘ + K

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Frequently asked questions

Read more

Version 1.0.0 · Updated 2026-08-09 · Runs entirely in your browser