pem vs ark-std

Short answerBy steady daily use, pem is bigger: 1,031,308 real downloads a day against 346,455 for ark-std (3.0x). 419 crates depend on pem and 361 on ark-std. pem last shipped 3 months ago, ark-std 6 months ago.

pem

Established

Established and gaining.

419 crates depend on it; downloads don't spike on releases.

Parse and encode PEM-encoded data.

ark-std

Established

Established and steady.

361 crates depend on it; no release in the last 90 days, so its count is all steady use.

A library for no_std compatibility

pemark-std · 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	pem	ark-std
Real downloads a day	1,031,308	346,455
Crates that depend on it	419	361
Last release	4.0.0, 3 months ago	0.6.0, 6 months ago
Trend vs the field	+11%	+3%
Release-window share	2.0%	0.0%
Downloads in the window	96,017,561	30,346,227
All-time downloads	358,147,003	111,569,649
Versions published	29	7
License	MIT	MIT/Apache-2.0
MSRV	1.71.0	not set
First published	Feb 27, 2016	Mar 24, 2021

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 (pem, 419 dependents): more eyes, more answered questions, and you may already have it in your tree.
Check the release dates against your own pace: pem 3 months ago, ark-std 6 months ago.

Also in this space

tinyvecEstablished`tinyvec` provides 100% safe vec-like data structures2,308,962 a day, 270 dependents siphasherEstablishedSipHash-2-4 and SipHash-1-3 keyed hash functions in pure Rust, with 64-bit and 128-bit output and no_std support1,957,258 a day, 274 dependents base64ctEstablishedPure Rust implementation of Base64 (RFC 4648) which avoids any usages of data-dependent branches/LUTs and...1,305,115 a day, 439 dependents pkcs1Pulled inPure Rust implementation of Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications...704,103 a day, 65 dependents

Compare 4 of them side by side →

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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