# time-rs/time: Rust date and time primitives

> The time crate provides Rust types and macros for working with dates, times, calendars, and durations. It targets Rust developers who need dedicated temporal data structures and compatibility with Rust 1.88.0 or newer.

**time-rs/time** — Date and time handling in Rust.

- Repository: https://github.com/time-rs/time
- Website: https://time-rs.github.io
- Stars: 1,344 · Forks: 314
- Language: Rust
- License: Apache-2.0
- Published: 2026-10-16 · Updated: 2026-10-16 · Language: en
- Canonical page: https://hysenlabs.com/projects/time-rs-time

## What time-rs/time solves in a Rust codebase

time-rs/time is a Rust library centered on date and time handling. Its workspace description identifies dates, calendars, and durations as core problem areas, while the package name and documentation links place it within the Rust ecosystem. The intended users are developers who need structured Rust values for temporal data rather than ad hoc strings, numbers, or date calculations.

The repository is not limited to a single binary or command-line program. Its top-level structure contains the main `time` package, `time-core`, and `time-macros`, with the default workspace member set to `time`. That separation shows a library organized around a public crate plus supporting packages. The repository metadata also lists `no-std` as a topic, although the repository files do not include the feature definitions needed to explain exactly how that mode is enabled or constrained.

The crate's scope makes it relevant to programs that store timestamps, represent calendar dates, calculate durations, or expose temporal values through Rust APIs. The README does not state whether it handles scheduling, recurring events, parsing arbitrary natural-language dates, or application-level timezone conversion. Those behaviors should be treated as unconfirmed until checked in the API documentation.

## Workspace architecture and package boundaries

The root `Cargo.toml` declares a Rust workspace with three members: `time`, `time-core`, and `time-macros`. `time` is the only default member, so ordinary workspace commands would treat the main package as the default target. The root package configuration uses edition `2024` and declares `rust-version = "1.88.0"`.

The workspace dependencies show that `time-core` and `time-macros` are linked to the workspace through path dependencies and pinned versions. The main package is therefore not represented as one isolated source file in the repository. Supporting crates and feature-specific dependencies, including `deranged`, `serde`, `serde_json`, and several `rand` versions, are visible in the workspace configuration.

This layout is useful when evaluating integration cost. Consumers normally need to understand the published `time` package, its feature flags, and whether `time-core` or `time-macros` are pulled in transitively. The repository files do not show the complete feature table or the public re-exports, so they cannot establish which types are available under each configuration. The main-branch API documentation is the appropriate place to verify those details.

## Rust version policy and compatibility constraints

The minimum supported Rust version is stated directly in the workspace configuration as `1.88.0`. The README also describes a policy: the project is guaranteed to compile with the latest stable Rust release and the two prior minor releases, with an exception allowing the minimum version to move to one of those supported versions or, when justified by code quality or maintainability, as far as four minor releases before the most recent stable release.

For a new Rust project, this creates a concrete compiler decision. A toolchain older than `1.88.0` is outside the repository's stated minimum. A current toolchain may work, but the README does not promise compatibility with every future or historic release. It also warns that the latest version of a third-party crate may not support the minimum supported Rust version of `time`. That distinction matters when `time` is combined with ecosystem dependencies that have different compiler policies.

The README states that a version of a third-party crate supporting the minimum Rust version will exist, but that is a compatibility policy rather than a guarantee that a particular dependency version already meets it. Teams integrating `time` should check the exact versions in their lockfile and build with the selected Rust toolchain.

## Installing time and completing the first documented step

The README does not give an installation command, `cargo add` invocation, Cargo.toml dependency snippet, or first-use program. It does identify the published package as `time` through the crates.io badge and links to the latest release documentation. It also links to the main-branch API documentation and the project book.

A reader looking for the supported installation path should start with the `time` documentation on docs.rs. The README does not establish the exact feature flags or package command to use, so this review does not invent them. The repository's `Cargo.toml` is a workspace manifest, not a complete consumer application manifest, and should not be copied wholesale into a new project.

The first concrete source of API guidance is the latest release documentation at `https://docs.rs/time`. The main-branch API is separately available at `https://time-rs.github.io/api/time`, while the repository links a book at `https://time-rs.github.io/book`. The distinction between release and main-branch documentation matters because the repository can change after a published version, and the README does not state whether their APIs are identical.

## Features and dependencies that need verification

The repository metadata includes the `no-std` topic, and the workspace manifest contains dependencies related to serialization, deserialization, testing, and randomized generation. `serde` and `serde_json` appear as workspace dependencies, while `deranged` is also listed. These names show areas for which the repository has integration or testing support, but the workspace manifest does not reveal whether each dependency is enabled by default or attached to optional features.

That omission is significant. A date and time crate can expose different behavior for serialization, platform support, macro-generated formats, or standard-library compatibility without changing its main type names. The repository files do not provide the feature declarations, so it would be inaccurate to promise `serde` support, `no-std` support, a particular allocation model, or support for a named platform based solely on dependency names and topics.

Before adoption, inspect the published `time` package's feature list and the API pages for the exact configuration. If the application already depends on a different version of `serde`, `deranged`, or another shared dependency, version resolution and lockfile compatibility also need checking. The workspace pins several dependency versions for its own development, but those pins do not by themselves describe every consumer configuration.

## Where time is a poor fit

The clearest limitation is documentation depth in the README. It explains the Rust version policy, documentation links, contribution process, and licensing, but it does not document timezone handling, daylight-saving behavior, leap seconds, parsing rules, formatting syntax, duration overflow, feature flags, or rollback behavior. Those omissions prevent a safe adoption decision based on the README alone.

The repository description is broad enough to be useful, but broad scope can also be misleading. It does not establish that `time-rs/time` is a replacement for a calendar scheduler, a database timezone layer, or a standards-compliant serialization service. A project whose primary requirement is timezone-aware scheduling should verify the API and semantics rather than infer them from the `date` and `time` topics.

There is also a compatibility boundary for Rust dependencies. The README explicitly says that the latest third-party crate does not necessarily support the minimum supported Rust version of `time`. An application pinned to older ecosystem versions may therefore face version resolution or compiler compatibility work. The repository does not provide a documented migration policy for such combinations.

## Alternative approach: standard-library and application-specific types

A practical alternative is to use Rust's standard-library facilities where the application only needs a narrow representation, then keep timezone, calendar, or parsing behavior in application-specific modules. This approach avoids adding a broad temporal crate when the required values are simple timestamps or fixed-duration counters. Its cost is that application code must define its own representation, validation, formatting, serialization, and edge-case policy.

The difference in approach is scope. `time-rs/time` presents a dedicated library with date, time, calendar, and duration keywords and a workspace for macros and core support. A standard-library-first design keeps dependencies smaller but leaves domain behavior distributed across the application. Which option is better depends on requirements that the README does not document, especially timezone semantics and feature configuration.

Another alternative is a different external date and time crate, but the README does not identify one, its API, or its compatibility policy. Comparing it by feature name alone would risk inventing differences. The defensible comparison here is between adopting a dedicated temporal data model and maintaining a narrower application-specific one.

## Maintenance, upgrades, and licensing

The repository is not archived. Its recorded last push is on 2026-10-15, which is close to the project date, but this review does not infer a maintenance commitment beyond that repository fact. Recent releases listed for the project are `v0.3.55` on 2026-08-01, `v0.3.54` on 2026-07-20, and `v0.3.53` on 2026-07-01. The README does not describe breaking changes between these releases or provide an upgrade procedure.

The root `Cargo.toml` declares `license = "MIT OR Apache-2.0"`, and the README states that the project is licensed under either the Apache License, Version 2.0 or the MIT license at the user's option. The repository includes separate `LICENSE-Apache` and `LICENSE-MIT` files. The README also states that contributions are dual licensed under those terms unless the contributor explicitly states otherwise. This identifies the licensing choices; it does not replace reviewing the license files for the intended distribution model.

Upgrade cost should therefore include more than changing a dependency version. Check the minimum Rust version, enabled features, shared dependency versions, API documentation, and serialization behavior before moving a production application to a newer release.

## Conclusion

Adopt time-rs/time when a Rust application needs dedicated date, time, calendar, or duration types and its documented APIs match the required behavior. Do not adopt it solely from the repository description, because the README does not provide an installation command, feature matrix, timezone model, or first-use example. Verify the published API documentation for the selected compiler and feature set first, then confirm that the crate's calendar and duration behavior fits the application.

## FAQ

### What is the minimum Rust version required by time-rs/time?

The workspace declares `rust-version = "1.88.0"`, so Rust 1.88.0 is the stated minimum supported version. The README describes a policy around the latest stable release and prior minor releases.

### How do I install the time crate?

The README does not document an installation command or Cargo.toml snippet. It links to the published package documentation at `https://docs.rs/time`, where the supported usage instructions are located.

### Which Rust packages make up the time workspace?

The workspace members are `time`, `time-core`, and `time-macros`, with `time` listed as the default member. The root manifest links the two supporting packages through path dependencies.

### What license does time-rs/time use?

The project is offered under either the Apache License, Version 2.0 or the MIT license at the user's option. The repository includes `LICENSE-Apache` and `LICENSE-MIT`.

## Sources

- [License: Apache-2.0](https://github.com/time-rs/time/blob/main/LICENSE)
- [Project website](https://time-rs.github.io)
- [README](https://github.com/time-rs/time/blob/main/README.md)
- [Releases](https://github.com/time-rs/time/releases)
- [time-rs/time on GitHub](https://github.com/time-rs/time)

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Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/time-rs-time