SongEngine is a free plug-in that specializes in two things:
The concept is simple:
Simply download the installer and install the plug-in on your system. Then open your DAW and add SongEngine to a track.
To import your own MIDI chord progressions, go to the "Chords" page, then click on "New..." (bottom right).
You can import files via drag and drop or via "Import chords from MIDI file...".
Your MIDI file should look like this:
Example:

If your chord progression doesn't contain dedicated bass notes (the lowest notes of the chords), then SongEngine will guess some good bass notes for you.
SongEngine contains several chord progression generator algorithms:
The plug-in will generate a first progression and display it on the "Chords" page. Click on the dice icon to generate another variation.
When you click on "More", you can see a "Lock scale" setting. When "Lock scale" is active and you click on the dice symbol, SongEngine will generate a chord progression for the currently chosen "Associated scale".
Tip: If you want to generate a chord progression for a specific scale, it's usually quicker to go back to the starting page, click on "Generate chord progression", and then choose "Generate for specific scale".
You can edit chord progressions on the "Chords" page. Press play in your DAW to listen to a preview.
Right-click on a chord to change the bass note or modify the chord if needed. You will also find some functions to change the whole chord progression at once here.
Use the handles at the start or end of a chord to make it longer or shorter.
You can move any note around (but only vertically). Double-click on a note to remove it, and double-click on an empty spot to create a new note. The colourful small lines at the beginning of the active chord will show you which notes are on the scale.
Click on the bottom bar to hear a preview of the chord. You can also find its detected name here.
The "Associated scale" setting will only affect some of the presets on the "Packages" page. It does not transpose the chords when you change the scale name or the root note! The key/scale setting is important for SongEngine to take the musical context of the progression into account. When you import a MIDI chord progression, the plug-in should guess the correct scale. However, if it detects the wrong scale, you can change it manually here.
At the bottom, you can find the Chord Pads area (see next section). Click on the triangle button to fold and unfold this area.
Chord Pads are an easy way to create new chord progressions quickly. Drag a pad to the chord progression area to either replace a chord (drop it at the beginning of an existing chord) or to insert a new chord (drop it somewhere else).
Click on any pad to hear a preview. You can right-click a pad to rename it, change its colour, or replace it. When a pad shows a bold stripe at the top left corner, this means that the pad contains notes that are outside of the current scale.
Click on the "More" button to see actions that affect the whole chord pad collection. You can save and load pads here, change the number of columns and rows, etc.
When you activate the "Flow" button (the button with the wavy icon next to the "More" button), the notes of each pad will automatically adjust to the existing chords of your chord progression. This way, you can create progressions where the notes "flow" from one chord to the next without large jumps. The voicing of the first chord of the progression will be used as a reference.
The "Pad Source" field shows the name of the currently active pad source collection. When you click on the name in the middle field, a new dialog will show up. In this dialog, you can load a pad collection that you would like to work with. Double-click on an entry to load it (or click on the OK button).
There are two main types of pad sources:
Of course, you can create your own Chord Pad collections as well. Simply edit the pads, then click on "More" (to the right of the "Pad Source" field) and choose "Save pads...".
You can switch between four banks of pad collections. Each collection can have its own Pad Source model.
You can save a chord progression to your hard drive or to the clipboard:
To load a chord progression:
When you click on "Packages", you will see a list of packages on the left side and a list of presets on the right side. Each preset belongs to a package.
Select a preset, then press play in your DAW to hear a preview.
You can find a search area and a settings area at the bottom. Click on the header bar to make all elements visible. Then do a search or click on a tag to see only presets with that tag. You can select multiple tags as well.
Each preset has a star-shaped "Favorite" marker. It is located to the left of the MIDI drag-and-drop field. Use the "Show favorites" tag in the tag browser to display your favorites only.
Below the "Favorite" star, you can find a preset type icon. Hover the mouse over the icon to read more about the preset type.
The three main types:
You can find a MIDI preview area on the right side of each preset. It displays the notes to give you a quick overview of the generated notes.
Drag and drop this MIDI area to your DAW to export the preset as a standard MIDI file. If your DAW doesn't support drag and drop, you can drag the MIDI file to an open Explorer window (Windows) or Finder window (macOS).
Not all presets will have the same length as your original chord progression. Some might be longer because the preset needs more time for melodic changes, modulations, or embellishments. The generated output will have the same meter as the original chord progression.
You can find the song parts area at the top. Initially, there is only one song part visible ("Verse"). You can do a double click to rename it.
Click on a "+" sign to duplicate a song part. Do a right-click to delete a song part or rename it.
The different song parts are completely independent from each other. You can create new chord progressions if you like, or you can simply use the same chord progression and test different presets in the "Packages" view.
If you use the VST version, you can route the generated notes to another synth via MIDI.
You can find instructions for different DAWs here (simply use SongEngine instead of ChordPotion ;).
Attention: The AU version doesn't support this feature. AU components can either operate as an audio plug-in or as a MIDI plug-in, but not as both.
Will SongEngine melodies always sound the same?
You can read more about this here.
On how many computers can I use my add-on/extension licenses?
You can use your licenses on as many computers as you like (as long as these computers belong to you). No need to uninstall anything when you switch to a new computer :). You can also use the same licenses for both macOS and Windows.
What is the best way to create an own Chord Pad Collection quickly?
Try this: