SAI is an advanced APK installer with split APK support. It also has simple app backup/export functionality.

SAI can install apps using standard Android API, using root access or using Shizuku.

SAI is an open-source app, you can get the source code on its GitHub repo - github.com/Aefyr/SAI

Please note that SAI only installs user-provided files and is not responsible for those apps behavior.
Please also note, that some devices/ROMs aren't supported by SAI, that has to do with bad Android API implementation in said ROMs and can't be fixed on app side.

From version Split APKs Installer (SAI) 4.5:

4.5:
• Added a setting to disable opening .apk files via SAI
• SAF fixes for Android 11
• Added warning when installing huge (>150MB) apps

4.4:
• Fixed in issue where system suggested SAI when opening any type of file
• Added Sui support for Shizuku Installer

Legendary SAI update Pog
4.3:
• Support for opening .apk files via SAI
• APKM support (only for the unencrypted .apkm files)
• Installer Pro mode is now enabled by default
• Config splits shouldn't be marked as Unknown anymore

All versions
Split APKs Installer (SAI) 4.5
February 25, 2021

Version:4.5

Uploaded:February 25, 2021 at 5:01PM UTC

File size:4.89 MB

Downloads:27,608

Split APKs Installer (SAI) 4.4

Version:4.4

Uploaded:February 1, 2021 at 8:43PM UTC

File size:4.85 MB

Downloads:2,129

Split APKs Installer (SAI) 4.3

Version:4.3

Uploaded:January 31, 2021 at 8:04AM UTC

File size:4.85 MB

Downloads:431

Split APKs Installer (SAI) 4.2

Version:4.2

Uploaded:June 18, 2020 at 3:19AM UTC

File size:4.83 MB

Downloads:29,642

Split APKs Installer (SAI) 4.1

Version:4.1

Uploaded:June 17, 2020 at 10:47PM UTC

File size:4.83 MB

Downloads:865

Split APKs Installer (SAI) 4.0

Version:4.0

Uploaded:June 5, 2020 at 3:48AM UTC

File size:4.52 MB

Downloads:8,971

Split APKs Installer (SAI) 3.12

Version:3.12

Uploaded:April 28, 2020 at 9:18PM UTC

File size:4.31 MB

Downloads:14,454

Split APKs Installer (SAI) 3.11

Version:3.11

Uploaded:April 22, 2020 at 5:05AM UTC

File size:4.31 MB

Downloads:2,696

Split APKs Installer (SAI) 3.10

Version:3.10

Uploaded:April 10, 2020 at 5:33AM UTC

File size:4.24 MB

Downloads:9,571

Split APKs Installer (SAI) 3.9

Version:3.9

Uploaded:March 27, 2020 at 10:48PM UTC

File size:4.05 MB

Downloads:5,436