Save converters can change a save from one format to another. Emulators can sometimes use a different file format.
.srm <-> .sav[]
https://savefileconverter.com/#/srm-sav - Convert .srm files to .sav and vice versa. If you have a save file from a specific place like the MiSTer, a flash cart, or a Retron 5 please use one of the converters below instead.
Game Boy Advance[]
Gameshark (*.sps): https://savefileconverter.com/#/gba/gameshark
Gameshark SP (*.gsv): https://savefileconverter.com/#/gba/gameshark-sp
Action Replay (*.xps): https://savefileconverter.com/#/gba/action-replay
gbaconv[]
Converts GBA battery saves between VBA-M and the VBA-Next core of RetroArch. Note that most games will work without conversion, but some may break entirely without converting (e.g. Ninja Five-O).
https://github.com/libretro/vba-next/tree/master/libretro/gbaconv
PS1[]
DexDrive (*.gme): https://savefileconverter.com/#/ps1/dexdrive
PS1 games on PSP (*.vmp): https://savefileconverter.com/#/ps1/psp
PS1 games on PS3 (*.PSV): https://savefileconverter.com/#/ps1/ps3
Emulator (*.mcr): https://savefileconverter.com/#/ps1/emulator
Memcard Rex: https://github.com/ShendoXT/memcardrex/releases
PS2[]
http://www.csclub.uwaterloo.ca:11068/mymc/
Nintendo 64[]
DexDrive (*.n64): https://savefileconverter.com/#/n64/dexdrive
Emulator (*.mpk): https://savefileconverter.com/#/n64/controller-pak
Sega CD[]
Emulator (*.brm, *.sav, etc): https://savefileconverter.com/#/sega-cd Change RAM cart size because some emulators only support certain sizes. Move internal memory saves to RAM cart or vice versa. Split up and recombine saves within a file as necessary.
Wii Virtual Console[]
Wii VC (*.bin): https://savefileconverter.com/#/wii
MiSTer[]
Various MiSTer platforms: https://savefileconverter.com/#/mister
Flash Carts[]
Everdrive, EZ Flash, Mega SD: https://savefileconverter.com/#/flash-carts
Nintendo Switch Online[]
Requires access to homebrew software on the Switch: https://savefileconverter.com/#/nintendo-switch-online
Online emulators[]
Various websites that allow you to play retro games in the browser. Most only allow the downloading of save states: https://savefileconverter.com/#/online-emulators
Be sure to make an in-game save before creating/downloading your save state. Only the in-game save can be extracted from the save state.
Retron 5 / RetroFreak[]
https://savefileconverter.com/#/retron-5
PSP (save decryption)[]
https://savefileconverter.com/#/psp
Nintendo DS[]
http://shunyweb.info/convert.php
Places to download save files[]
https://savefileconverter.com/#/download-saves