Registered developers with a paid or free developer account can download beta IPSW restore images directly from the Apple Developer Download page
If you want to know how to back to a stable version or need help identifying your specific device model , just let me know! download ios beta ipsw
If Apple is no longer signing an old beta, but you still need it for testing, use trusted developer archives: Registered developers with a paid or free developer
: Released first; intended for app testing. IPSW files are readily available here for clean installations. download ios beta ipsw