Crates / castaway / Alternatives
Rust crate alternatives · data Oct 24, 2026
Alternatives to castaway
Short answerThe closest alternatives to castaway on crates.io data are zerocopy (3.2M real downloads a day), num-conv (2.1M real downloads a day), cast (789K real downloads a day). Of the 8 we list, the most used is thiserror, and 7 shipped a release in the last year. castaway itself gets 626,291 a day with 25 dependents.
Every alternative we found
| Alternative | Real downloads a day | vs castaway | Dependents | Last release | Why it is listed | |
|---|---|---|---|---|---|---|
| zerocopy Established | 3,245,504 | 5.18x | 878 | 11d | category Rust patterns, keyword "cast" | compare |
| num-conv Pulled in | 2,114,479 | 3.38x | 4 | 5mo | category No standard library, category Rust patterns, keyword "cast" | compare |
| cast Established | 788,776 | 1.26x | 108 | 5.1y | keyword "cast" | compare |
| thiserror Foundational | 5,048,791 | 8.06x | 75,923 | 31d | category No standard library, category Rust patterns | compare |
| itertools Widely used | 4,545,996 | 7.26x | 8,656 | 4mo | category No standard library, category Rust patterns | compare |
| once_cell Widely used | 3,785,180 | 6.04x | 8,656 | 7mo | category Rust patterns | compare |
| pin-project-lite Widely used | 3,270,978 | 5.22x | 1,708 | 8mo | category No standard library, category Rust patterns | compare |
| anyhow Foundational | 2,875,638 | 4.59x | 52,113 | 3mo | category No standard library, category Rust patterns | compare |
How to choose
- Same job, not the same API. Each line is listed because it shares a crates.io category or keyword with castaway; read its description before you swap.
- More dependents means more answered questions and a smaller chance it disappears.
- Check the last release against how fast you need fixes. For castaway: is it still maintained?
Rules
Alternatives = tracked crates (top 1000 by downloads) that share a specific crates.io category (2 points each) or keyword (3 points each) with castaway, most similar first; its own parts (same name prefix) and crates it depends on or that depend on it are left out, because those are companions, not substitutes. Real downloads = quiet-day median, crates.io data Oct 24, 2026. Built when we find 3 or more.
Up next
The closest alternative: Established and steady. 3,245,504 real downloads a day.zerocopyRust crate. Zerocopy makes zero-cost memory manipulation effortless. We write "unsafe" so you don't have to. Real use: 3.2M downloads a day on quiet days; 878 crates...Read it next →Also worth your time