Top 5 JWT Parsing Errors
1. **Missing Bearer Prefix**: Passing `"Bearer eyJ..."` directly into a decoder instead of stripping `"Bearer "`.
2. **Incorrect Part Count**: Having fewer or more than 2 dots (must be exactly 3 segments).
3. **Standard Base64 vs Base64URL**: Standard Base64 contains `+` and `/`, which are invalid in Base64URL without conversion to `-` and `_`.
4. **UTF-8 Encoding Corruption**: Non-ASCII characters in claims decoded without multi-byte TextDecoder.
5. **Truncated Tokens**: HTTP header length limits or database column truncation clipping the signature.
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Frequently Asked Questions
How do I test my token against these errors?
Paste your token into our client-side JWT Decoder. It will parse each segment individually and highlight exact syntax or formatting anomalies.
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