Encode and decode small data-payloads using filename and URL-safe characters

1.0.0 2017-02-03 11:48 UTC


This library lets you encode and decode small data-payloads into strings that can be safely used in filenames and URLs.

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This can be useful for things like encoding resize/cropping-information into image URLs, creating personalized URLs for sharing things, etc.

The generated strings contain a small checksum as an integrity-check only - do not rely on this for "security by obscurity", the data-payload can be decoded and is by definition not secure or private in any way.

With that said, there is an option to prevent brute-force attacks, e.g. using a longer checksum and private salt - see options below.


The service itself has no dependencies:

$service = new PayloadService();

To encode an array as a string:

$string = $service->encode(["hello" => "world"]); // "cMIDaGVsbG89d29ybGQ"

And to decode the string back to an array:

$data = $service->decode("cMIDaGVsbG89d29ybGQ") // ["hello" => "world"]


The constructor permits you to optionally enforce a maximum encoded length - this option is disabled by default. If enabled, encode() will throw if the encoded string-length is over the defined maximum.

You can optionally specify number of characters to append as a checksum - this is set to 4 by default. If you don't care about URL integrity, you can set this to zero.

If you're concerned about brute-force attacks against URLs, you can increase the checksum size, and optionally specify a private salt to seed the checksum - again, this does not provide strong security, but enough to prevent e.g. brute-force attacks against image URLs.

Refer to the source-code for inline documentation of options.


Only strings and arrays can be encoded. If your data contains integers, these will be converted to strings, and will arrive in string format when decoded.

Some Advice

Avoid encoding strings such as filenames, if you can - because the data is encoded in base64 format, it will increase in size, so a good filename strategy could be (for example) using an encoded string a prefix or suffix to a filename.