WebSocket Frame Calculator

Encode and decode RFC 6455 frames locally, inspect header fields, masking, payload lengths, close data, and fragmentation.

Protocol scope: RSV bits are treated as errors because no extensions are negotiated. Client-to-server frames must be masked; server-to-client frames normally are not. This page makes no network connections.

Encode one frame

Opcode

Payload input

FIN Mask as client frame

Payload

Mask key (4-byte hex)

Raw frame (hex)

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Raw frame (Base64)

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Header fields

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Decode frame sequence

Raw input format

Expected sender

One or more concatenated framesMaximum decoded frame sequence: 1 MiB payload and 1,024 frames.

No sequence decoded.

#	Header	Type	Length	Mask	Decoded payload