How to build a DJ library without buying filler
Filler is music you bought and never play. How to measure your own filler rate, shop for gaps, and give new purchases a probation period in rekordbox.
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A DJ library without filler is built from the sets backwards. Before you buy, know which gap a track fills. After you buy, give it a few weeks to prove itself in your mixes. Then check what you actually played, and let that shape your next shopping list. Filler gets in when buying runs ahead of playing, so the fix is to keep the two in step.
What filler looks like
Filler is music you own but never reach for. It rarely comes from bad taste. Usually it slips in through one of a few doors:
| How it gets in | What it looks like later | The check that stops it |
|---|---|---|
| One great moment in someone's mix | A track that only worked in that blend | Hear it alone, start to finish, before you buy |
| Chart-chasing | Tracks that felt urgent the week you bought them | Beatport's Top 100 and Genre Top 100 update every day based on sales, so a chart is a snapshot, not a verdict |
| A second track for the same job | Two near-identical rollers, one never played | Ask what you already own that does this job |
| The wrong version | A radio edit with no intro, or a remix you didn't mean | Write the mix name down when you first hear the track |
| "Might need it someday" | A genre you don't play out | Buy for the sets you play now |
Measure your own filler rate
Before you change how you buy, find out how much filler you've already got. You only need two lists.
- What you bought. Use your store order histories, or sort your library by date added, and list the tracks from the last three months.
- What you played. rekordbox keeps a history of tracks played for a minute or more in PERFORMANCE mode or through LINK EXPORT, and you can right-click a history to copy it to a playlist. Gather the histories from the same three months.
Compare the two. Here's a made-up example of the arithmetic: if you bought 60 tracks and 18 of them appear in any history, 30% of your purchases made it into a mix, and 42 tracks haven't been played yet. There's no correct target. The number is a baseline you can watch over the next few months.
Will Lynch, writing for Pioneer DJ about managing music, also suggests showing a play count column in rekordbox to see how few times you've played tracks you love. It's a quick way to spot what you've stopped reaching for.
Shop for gaps, not for tracks
Histories show more than what you played. They also show where you struggled. Look at a few recent sets and note the moments where you searched too long or settled for something that didn't fit: the first twenty minutes of a warm-up, a way to bring the tempo down, a vocal to lift the room.
Those moments are your shopping list. Write them down as jobs, for example "two long-intro openers around 120 BPM" or "one tool to bridge from house into techno". When you dig, a track either fills one of those gaps or it waits.
This doesn't stop you buying music you love that fits no gap. It makes that a conscious exception rather than the default.
Three questions at checkout
The full listening checklist lives in How to decide which tracks to buy. At checkout, three questions catch most filler:
- Which gap does it fill? If you can't name one, it goes back on the list.
- Will you play it in the next month? If you can't picture the set, it can wait. The track will still be in the store next week.
- Is this the version you heard? Check the mix name and length against your note.
Two habits help. Run the duplicate check before paying, because owning a track twice is the purest form of filler. And keep your basket small enough to learn. As a suggestion, buy no more tracks in a week than you can listen to properly and prepare before the weekend.
Give new tracks a probation period
Buying a track doesn't mean it has earned a permanent spot. Put every new purchase on probation:
- A probation shelf. In rekordbox, create an Intelligent Playlist with a date rule. Lynch's example uses a date-added range. The manual also describes an "is in the last" condition, which lists tracks whose date (its example is a release date) falls within a number of days or months of today, so the shelf can roll forward without editing.
- A tag for "played out". rekordbox's My Tag lets you create your own tags and filter by them. Add a tag such as Played out the first time a track works in a real set.
- A verdict at the end. When a track leaves the probation window without the tag, decide: keep it for a specific job, or archive it.
Archiving doesn't mean deleting. rekordbox's manual notes that removing a track from the Collection doesn't delete the file from your computer, and stores like Beatport let you re-download purchases. Keep the archive outside the library you DJ from, so it stops adding lines to every search.
Review every few months
Every quarter or so, repeat the filler measurement and look at the trend.
- Filler rate going down: your gap list and checkout questions are working.
- Lots of tracks played once: you might be buying for novelty. Check whether they came from one source, such as a chart or a single DJ's sets.
- Big unplayed backlog: buy less until you've caught up on preparing and playing what you have.
Lynch puts the payoff simply: "you'll always play better with a smaller crate full of music you know inside and out". For the bigger picture of how many tracks you need, see How many tracks do you need for a DJ set?. For where new purchases go once they've passed, see the pillar guide on organizing new music before it hits your DJ library.
Doing this with CatchIt!
CatchIt! is a Mac app with a free iOS companion. It works on the buying side, before files exist. It doesn't read your rekordbox histories or manage your library.
- Reject on record. Return keeps a track (green) and Space rejects it (red). Rejected tracks stay on record, and a repeat find shows its previous decision.
- A second cut. In the Wishlist, Demote → Red sends a kept track back to rejected when it fails your checkout questions.
- Done means bought. Mark tracks Done when you buy them, and filter the Wishlist by Pending or Done to see what's still waiting.
See Core concepts.
Frequently asked questions
- How do I build a DJ music library from scratch?
- Start with the sets you want to play, not with a shopping spree. List the jobs you need tracks for (openers, long blends, peak-time tracks, closers), buy a few strong tracks for each, learn them, and add more only where you keep running short.
- What counts as filler in a DJ library?
- Any track you own but never reach for. Typical sources are impulse buys from a single great moment in a mix, chart-chasing, a second track that does the same job as one you already have, and the wrong version of a track you wanted.
- How can I tell which tracks I actually play?
- rekordbox keeps a history of tracks played for a minute or more in PERFORMANCE mode or via LINK EXPORT, and you can copy a history to a playlist. Compare a few months of histories with what you bought in the same period.
- Should I delete tracks I never play?
- Take them out of the library you DJ from, but keep the files in an archive. rekordbox's manual notes that removing a track from the Collection doesn't delete the music file from your computer.
Sources
- Pioneer DJ (Will Lynch): How to find music you love, in a way that you love
- Pioneer DJ (Will Lynch): How to manage your music like a pro
- rekordbox 7.2.18 Operating Instructions (PDF)
- Beatport Support: How often do the Beatport Top 100 and Genre Top 100 charts get updated?
- Beatport Support: How do I re-download my tracks?