Crates / Compare / indexmap vs smallvec
Rust crates side by side · data Oct 24, 2026
indexmap vs smallvec
Short answerBy steady daily use, indexmap is bigger: 4,883,122 real downloads a day against 3,868,589 for smallvec (1.3x). 6,422 crates depend on indexmap and 4,345 on smallvec. indexmap last shipped 49 days ago, smallvec 1 day ago.
indexmap
Widely usedWidely used and steady.
6,422 crates depend on it; downloads don't spike on releases.
A hash table with consistent order and fast iteration.
smallvec
Widely usedWidely used and steady.
4,345 crates depend on it; downloads don't spike on releases.
'Small vector' optimization: store up to a small number of items on the stack
indexmapsmallvec · 100% = that crate's normal quiet day, so a spike to 300% is triple its usual traffic
How they relate
- Often used together: 5 tracked crates depend on both (schemars, serde_with, pyo3, sqlx-core, rkyv). They are not always either/or.
Every number, side by side
| Same window, same method | indexmap | smallvec |
|---|---|---|
| Real downloads a day | 4,883,122 | 3,868,589 |
| Crates that depend on it | 6,422 | 4,345 |
| Last release | 2.14.2, 49 days ago | 1.16.4, 1 day ago |
| Trend vs the field | -3% | -2% |
| Release-window share | 3.5% | 18.8% |
| Downloads in the window | 428,873,022 | 339,700,171 |
| All-time downloads | 1,746,777,511 | 1,348,060,732 |
| Versions published | 57 | 86 |
| License | Apache-2.0 OR MIT | MIT OR Apache-2.0 |
| MSRV | 1.85 | not set |
| First published | Jan 30, 2018 | Apr 6, 2015 |
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 (indexmap, 6,422 dependents): more eyes, more answered questions, and you may already have it in your tree.
- Check the release dates against your own pace: indexmap 49 days ago, smallvec 1 day 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.
Up next
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