Crates / once_cell_polyfill
Rust crate · real downloads · data Oct 24, 2026
once_cell_polyfill downloads, and should you depend on it?
Polyfill for `OnceCell` stdlib feature for use with older MSRVs crates.io · docs.rs · repository
Owned on crates.io by epage · is it still maintained?
Few direct dependents and losing ground.
once_cell_polyfill: only 3 crates name it directly; most of its downloads come in through anstyle-wincon; no release in the last 90 days, so its count is all steady use.
How this verdict is decided (4 rules)
- Usage: crates.io reverse dependencies (crates that list it as a dependency): 10,000+ = foundational, 1,000+ = widely used, 100+ = established, under 100 = few direct dependents.
- Direction: the median quiet day in the last 30 days of the window against the first 30, read against the median tracked crate (the whole field moved +39% from late summer to October, so a raw trend says nothing). 10%+ ahead of the field = gaining; 10%+ behind = losing ground; otherwise steady. Steady with no release in 2+ years = quiet for years.
- Release spikes: the median release-window day against the quiet-day baseline: under 1.15x = no spike, 1.15x to 1.3x = small bumps, 1.3x or more = jumps on release days.
- Release recency: days since the newest version that was not yanked, from crates.io publish times.
release window (release day + next day)quiet dayquiet-day median · download the 89 days as CSV
The numbers in one paragraphonce_cell_polyfill got 89,478,071 crates.io downloads from Jul 27, 2026 to Oct 23, 2026 with no new version in that window, so every day is a quiet day: a median of 1,102,539 a day, about 7,717,773 a week. With no release spikes to remove, its whole count is the steady baseline.
What this means if you're choosing a dependency
- You rarely add this one yourself. Only 3 crates name it directly; its downloads arrive through anstyle-wincon.
- No release in over a year (last: 1.56.1, Oct 21, 2025). Fine for a finished crate; check open issues and the latest commit before relying on it.
- Fit check: license MIT OR Apache-2.0, edition 2021, needs Rust 1.56.0 or newer (from the latest version's manifest).
- Its raw count is a fair read. Under 1% of its downloads in the window came from release windows, so the raw number and the baseline (1,102,539 a day) tell the same story.
Its place in the dependency graph
Built on once_cell_polyfill
1 of the 1000 crates we track depend on it directly (biggest first).
What the chart says
- Weekend quiet days ran at 51% of weekday quiet days (586,792 vs 1,160,811). A dip that deep is the signature of work-week CI pipelines and developers building on weekdays.
- Biggest day: 1,379,669 on Oct 2, 2026, a quiet day with no release nearby.
Every number
| All-time downloads | 237,127,352 (rank #522 on crates.io by all-time downloads) |
| Downloads in the window | 89,478,071 (Jul 27, 2026 to Oct 23, 2026, 89 days) |
| Within 2 days of a release | 0 (0.0%) |
| Quiet-day median (baseline) | 1,102,539 a day; weekdays 1,160,811, weekends 586,792 |
| Release-adjusted downloads | 89,478,071 (release-window days capped at the baseline) |
| Baseline rank | #352 of the 1000 crates we track |
| Quiet-day trend | +20% raw, -14% against the median tracked crate (+39%) |
| Releases in the window | 0 |
| Versions published, ever | 5 |
| Latest version | 1.56.1, published Oct 21, 2025 (license MIT OR Apache-2.0, edition 2021, MSRV 1.56.0) |
| First published | May 22, 2025 |
| Reverse dependencies | 3 |
How we compute this
crates.io counts every download, including CI runners, mirrors and bots that fetch each new version, so raw counts run high (why, in The Manual). We split the last 89 days into release windows (the day a version of once_cell_polyfill was published, plus the next day) and quiet days, and use the median quiet day as the baseline: an upper bound on steady use, never a head count. The method and data come from our study of 90 days of crates.io data from 69 crates, featured in This Week in Rust #674; check any crate live with the real-downloads checker.
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Categories
Sources
- Daily downloads: crates.io API, /crates/once_cell_polyfill/downloads (last 90 days, all versions), fetched Oct 24, 2026.
- Versions and publish times: crates.io API, /crates/once_cell_polyfill/versions, same fetch.
- Reverse dependencies: crates.io reverse dependencies, same fetch. Dependency edges between tracked crates: each crate's default version, crates.io API.
- Fetched politely (one request every 2 seconds, identified User-Agent) per the crates.io data access policy. Data is crates.io's; the release-window split, baseline and verdict rules are ours, CC BY 4.0.
Up next
Next by real downloads: The next crate down the real-downloads ranking: 1,101,806 a day. Established and steady.serde_path_to_errorRust crate. Path to the element that failed to deserialize. Real use: 1.1M downloads a day on quiet days; 642 crates depend on it.Read it next →Also worth your time