Crates / Compare / p256 vs p384
Rust crates side by side · data Oct 24, 2026
p256 vs p384
Short answerBy steady daily use, p256 is bigger: 724,299 real downloads a day against 391,839 for p384 (1.8x). 1,172 crates depend on p256 and 378 on p384. p256 last shipped 4 months ago, p384 4 months ago.
p256
Widely usedWidely used and steady.
1,172 crates depend on it; no release in the last 90 days, so its count is all steady use.
Pure Rust implementation of the NIST P-256 (a.k.a. secp256r1, prime256v1) elliptic curve as defined in SP 800-186, with support for ECDH, ECDSA signing/verification, and general purpose curve arithmetic
p384
EstablishedEstablished and gaining.
378 crates depend on it; no release in the last 90 days, so its count is all steady use.
Pure Rust implementation of the NIST P-384 (a.k.a. secp384r1) elliptic curve as defined in SP 800-186 with support for ECDH, ECDSA signing/verification, and general purpose curve arithmetic support.
p256p384 · 100% = that crate's normal quiet day, so a spike to 300% is triple its usual traffic
How they relate
- Often used together: 1 tracked crate depend on both (jsonwebtoken). They are not always either/or.
Every number, side by side
| Same window, same method | p256 | p384 |
|---|---|---|
| Real downloads a day | 724,299 | 391,839 |
| Crates that depend on it | 1,172 | 378 |
| Last release | 0.14.0, 4 months ago | 0.14.0, 4 months ago |
| Trend vs the field | +3% | +11% |
| Release-window share | 0.0% | 0.0% |
| Downloads in the window | 66,216,309 | 37,477,410 |
| All-time downloads | 215,798,458 | 107,471,686 |
| Versions published | 61 | 52 |
| License | Apache-2.0 OR MIT | Apache-2.0 OR MIT |
| MSRV | 1.85 | 1.85 |
| First published | Oct 3, 2018 | Oct 3, 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 (p256, 1,172 dependents): more eyes, more answered questions, and you may already have it in your tree.
- Check the release dates against your own pace: p256 4 months ago, p384 4 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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