Check it out at https://dscd.link!
A web page that shortens given cdn.discordapp.com/attachment/.. and discord.com/channels/ links to point towards the page and redirects those generated links to the proper Discord attachment link afterward.
Technology
Uses NodeJS. Converts the data in the link from BigInt to Base64 to shorten it, and reverses that to redirect the user to the original file.
How Effective is the Link Shortening?
Parts of the URL that contain server, channel, or message codes are shortened by about 7 characters. File names are left untouched for readability's sake (users will have an idea of what they are clicking on when they see a shortened link). cdn.discordapp.com and discord.com are shortened to dscd.link (a shortening of 9 characters and 2 characters, respectively).
Example shortened links: https://cdn.discordapp.com/attachments/763533415978762261/925208250020933652/Dreamcast_Swirl.jpeg -> https://dscd.link/file/CpidmLGOABU/DNcAAF3CMBQ/Dreamcast_Swirl.jpeg (shortened by 30 characters) https://discord.com/channels/713671901985243137/763533415978762261/925208250188714034 -> https://dscd.link/msg/Ced40EwCAAE/CpidmLGOABU/DNcAAGfCUDI (shortened by 28 characters)
I'd say that's a pretty significant reduction!