Get your data
Spotify keeps your full listening history and gives it to you on request. Here's exactly how to ask for it.
Request the export
Open your Spotify privacy settings
Go to spotify.com/account/privacy ↗ and log in. (From the account page it's under Security and privacy → Account privacy.)
Tick "Extended streaming history"
Scroll to Download your data. Tick the box for Extended streaming history. That's the one with every play since you made your account, including skips, shuffle and devices.
You can untick "Account data" and "Technical log information"; TuneSummary doesn't need them. If you only want a quick look, "Account data" alone arrives sooner but covers just the last year with less detail.
Press "Request data"
Spotify sends you an email titled something like "Confirm your data request". Open it and press Confirm. Nothing happens until you do.
Wait
Spotify says it can take up to 30 days; it usually takes a few. When it's ready you get an email, "Your Spotify data is ready to download". The download link in it works for 14 days.
Download and upload
Download
my_spotify_data.zip. Don't unzip it. Upload it to TuneSummary →Your browser opens the zip and sends only the play history files' contents (track, artist, album, time, length, skip/shuffle, device type, country). Everything else stays on your device.