Take a look at the software chesspositiontrainer
Best software to maintain opening repertoire

Droidfish with an ECO PGN. I use SCID on computer, but I'm rarely on there anymore. I don't like paying for software much lol

There are really two options here. The first is, as Die_Schanze said, Chess Position Trainer. Really great software and the free version will maintain your repertoire perfectly. You will get full access to the whole program for a month, during which you can explore the spaced repetition training options fully. After a month, the training will still be there, but limited to a depth of 15 moves or something like that (among some other limitations -- but the repertoire maintenance will still work fully).
The other option is Lucas Chess, which has a feature called Personal Opening Guide. You can enter your repertoire in different sections and then you can create training modules from there and run through it in the "Learn Tactics by Repetition" module of Lucas Chess. Lucas Chess is 100% free and great software.
There are a few other options, but I don't recommend them.

The android app "Chess Repertoire Trainer" is another option if you are looking for a mobile app . It allows you to create openings and it supports PGN file import. You can also train/drill your openings. The GUI is very intuitive and easy to use. This app is new and is available on the Google Play Store.
Interesting.

Hi,
Sorry to wake up this old post but I wanted to notify the author of this post that a new tool is available to help you build, maintain and memorize your repertoire.
It's a free web application, no ads, nothing to download, mobile friendly...
Give it a try - > https://chess-repertoire-companion.com
Cheers

If you want the best software it's clearly chessbase. It does do repertoire training, along with anything else you can think of... like the ability to save your repertoire as different file formats which allows you to export it to other tools. And you don't necessarily have to use just one tool, you can use multiple.
I have started using this free website, it’s great! You can get model games for any opening you play, import moves from your games to start up your repertoire quickly. Easy to get started with, very instructive. You can practice any line you want. This is easily the best way to create, practice and maintain opening repertoire.

Hi,
Sorry to wake up this old post but I wanted to notify the author of this post that a new tool is available to help you build, maintain and memorize your repertoire.
It's a free web application, no ads, nothing to download, mobile friendly...
Give it a try - > https://chess-repertoire-companion.com
Cheers
Did you write this?
What are the advantages of this over - for example - chessable?

Hi,
Sorry to wake up this old post but I wanted to notify the author of this post that a new tool is available to help you build, maintain and memorize your repertoire.
It's a free web application, no ads, nothing to download, mobile friendly...
Give it a try - > https://chess-repertoire-companion.com
Cheers
Did you write this?
What are the advantages of this over - for example - chessable?
I did create Chess Repertoire Companion, and I'm glad you're interested in exploring it. While there are several tools available for building and maintaining chess repertoires, CRC focuses on simplicity, flexibility, and being a free, web-based application without any ads. It's designed to be mobile-friendly for users who prefer managing their repertoires on the go.
As for how it compares to Chessable, both tools have their unique features and strengths. Chessable is well-known for its extensive library of interactive courses and a structured learning path. On the other hand, Chess Repertoire Companion aims to provide a straightforward and user-friendly platform primarily dedicated to building, maintaining, and memorizing your repertoire without providing any embedded learning content. CRC is open-source and everybody can participate to improve the app and add new features.
Ultimately, the choice between the two would depend on individual preferences and the specific features that best align with your learning style and goals.
Feel free to give Chess Repertoire Companion a try, and if you have any questions or feedback, I'm here to help!
Cheers, Jeremy
I use "Chess Assistent pro 15" to maintain my opening repertoire. It´s ok. What do you recommend ?