Crates / Compare / bumpalo vs slotmap
Rust crates side by side · data Oct 24, 2026
bumpalo vs slotmap
Short answerBy steady daily use, bumpalo is bigger: 1,968,716 real downloads a day against 345,609 for slotmap (5.7x). 546 crates depend on bumpalo and 545 on slotmap. bumpalo last shipped 5 months ago, slotmap 11 months ago.
bumpalo
EstablishedEstablished and steady.
546 crates depend on it; no release in the last 90 days, so its count is all steady use.
A fast bump allocation arena for Rust.
slotmap
EstablishedEstablished and steady.
545 crates depend on it; no release in the last 90 days, so its count is all steady use.
Slotmap data structure
bumpaloslotmap · 100% = that crate's normal quiet day, so a spike to 300% is triple its usual traffic
Every number, side by side
| Same window, same method | bumpalo | slotmap |
|---|---|---|
| Real downloads a day | 1,968,716 | 345,609 |
| Crates that depend on it | 546 | 545 |
| Last release | 3.20.3, 5 months ago | 1.1.1, 11 months ago |
| Trend vs the field | -2% | +5% |
| Release-window share | 0.0% | 0.0% |
| Downloads in the window | 178,468,352 | 32,486,399 |
| All-time downloads | 667,112,303 | 121,116,845 |
| Versions published | 56 | 21 |
| License | MIT OR Apache-2.0 | Zlib |
| MSRV | 1.71.1 | 1.58.0 |
| First published | Nov 24, 2018 | Jul 2, 2018 |
Which to pick
- Downloads tell you what is common, not what fits. Each crate's own description above says what it is for; when the jobs differ, pick by the job.
- When both fit, prefer the one more crates depend on (bumpalo, 546 dependents): more eyes, more answered questions, and you may already have it in your tree.
- Check the release dates against your own pace: bumpalo 5 months ago, slotmap 11 months ago.
Also in this space
Method
Real downloads = the median day with no release that day or the day before, from the crates.io API (Jul 27, 2026 to Oct 23, 2026). Raw crates.io counts include CI and bots and run high (why); the method is from our 90-day study.
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