Base64 in Swift

How to encode and decode Base64 in Swift — with copy-paste examples and a live converter to check your output.

Swift's Foundation Data type has built-in Base64 support: base64EncodedString() to encode and Data(base64Encoded:) to decode.

Encode to Base64 in Swift

Swift

import Foundation

let encoded = Data("Hello, World!".utf8).base64EncodedString()

Decode Base64 in Swift

Swift

import Foundation

if let data = Data(base64Encoded: encoded) {
    let text = String(data: data, encoding: .utf8)
}

Notes & gotchas

Data(base64Encoded:) returns an optional and fails (returns nil) on invalid input rather than throwing. Foundation has no built-in URL-safe variant — swap "+/" for "-_" and re-pad manually if you need one.

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Base64 in Swift — FAQ

How do I Base64 encode a string in Swift?+

Use the code shown above. Data(base64Encoded:) returns an optional and fails (returns nil) on invalid input rather than throwing. Foundation has no built-in URL-safe variant — swap "+/" for "-_" and re-pad manually if you need one.

How do I decode Base64 back to text in Swift?+

Use the decode snippet above. Base64 decoding is lossless, so you get the exact original bytes back; decode them with UTF-8 to recover text.

Is Base64 encoding the same across programming languages?+

Yes. Base64 is a standard (RFC 4648), so a string encoded in one language decodes correctly in any other. Only the API differs, not the output.

Does Base64 secure my data?+

No. Base64 is an encoding, not encryption — anyone can decode it. Never use it to protect secrets.