Encode and decode base64, base64url, hex, and percent-encoding via @mukundakatta/base64-mcp (npx)

Recipe: Encode/decode base64, base64url, hex, and percent-encoding

Server: @mukundakatta/base64-mcp v0.1.1 Transport: stdio via npx @mukundakatta/base64-mcp Auth: none required Tools: 1 — transform Schema: { text: string, operation: "encode" | "decode", encoding?: "base64" | "base64url" | "hex" | "percent" } (encoding defaults to base64)

IMPORTANT: This server uses operation and encoding as parameter names — NOT op and flavor (which the sibling encoding-mcp uses). Passing op/flavor silently fails with "unsupported operation: undefined."

Verified trace (7 calls, 100% success)

base64 encode:

→ { name: "transform", arguments: { operation: "encode", encoding: "base64", text: "Hello, World! This is a secret message." } }
← { result: "SGVsbG8sIFdvcmxkISBUaGlzIGlzIGEgc2VjcmV0IG1lc3NhZ2Uu" }

base64 decode (roundtrip):

→ { operation: "decode", encoding: "base64", text: "SGVsbG8sIFdvcmxkISBUaGlzIGlzIGEgc2VjcmV0IG1lc3NhZ2Uu" }
← { result: "Hello, World! This is a secret message." }

base64url encode (URL-safe, no padding — ideal for JWT):

→ { operation: "encode", encoding: "base64url", text: "subjects?id=42&token=abc+def/ghi" }
← { result: "c3ViamVjdHM_aWQ9NDImdG9rZW49YWJjK2RlZi9naGk" }

hex encode:

→ { operation: "encode", encoding: "hex", text: "Hello" }
← { result: "48656c6c6f" }

hex decode (roundtrip):

→ { operation: "decode", encoding: "hex", text: "48656c6c6f" }
← { result: "Hello" }

percent encode:

→ { operation: "encode", encoding: "percent", text: "name=John Doe&city=New York" }
← { result: "name%3DJohn%20Doe%26city%3DNew%20York" }

percent decode (roundtrip):

→ { operation: "decode", encoding: "percent", text: "name%3DJohn%20Doe%26city%3DNew%20York" }
← { result: "name=John Doe&city=New York" }

Claude Code config

{ "mcpServers": { "base64": { "command": "npx", "args": ["-y", "@mukundakatta/base64-mcp"] } } }