Feature Request: Option to exclude ambiguous characters from generated short codes

[mfcarroll]

Currently, Rushomon uses a standard base 62 alphabet for generating random short codes. While this maximizes the namespace, it includes visually ambiguous characters (such as 0 vs O, and 1 vs l vs I).

For use cases where short URLs are frequently printed on physical media, displayed on screens, or shared verbally, these characters can cause confusion and lead to broken link visits.

Proposed Solution

I would like to propose adding an instance-level setting to exclude ambiguous characters. When enabled, the link generator would omit easily confused characters, likely following a standard base 58 alphabet approach which removes 0 (zero) O (capital o) I (capital i) and l (lowercase L).

Implementation Details

1. Add a new boolean setting (e.g., exclude_ambiguous_chars) to the settings database table.
2. Add a toggle switch to the Admin Settings UI.
3. Update src/utils/short_code.rs to support two alphabets: the current BASE62_CHARS and a new BASE58_CHARS, selecting between them based on the active setting.

An alternative could simply be to switch to base 58 completely, which would not significantly impact namespace availability, but this implementation would preserve the existing default.

[mfcarroll]

Thinking about this more if it should likely be an organization specific setting rather than instance-wide.

[piffio]

Yes, it's probably org specific, but also.... for printing I'd expect people to use the QR codes to avoid people having to type long and meaningless strings of characters.

Also, keep in mind that in the self-hosted version you can use your own custom code, i.e. using words that are easier to understand and type correctly.

I'm not outright opposing the suggestion, but I'm not sure it will add significant benefits on top of the alternatives that are already available.

Can yoy help me better understand your thinking here?

[mfcarroll]

Totally. It's a different use case to custom codes or print. Custom codes are great when one of our team creates a url themselves manually, e.g. for a social media post. At other times we will be automatically generating codes via the API, and still want those to be unambiguous.

An example would be automatically shortening the url for a zoom meeting. To access the meeting on a different (e.g. personal) device, entering a short link in the browser is quicker than typing in the full 11 digit meeting number plus passcode. QR codes play a useful role in many cases, but in some instances it's still helpful to provide a text link they can enter somewhere with a few characters, and for those, we want to avoid l / I confusion. It's definitely not a common use case, but still one we'd find useful. The setting would go on the organization settings page, in the Link Defaults section.