head to head · open source
Apache SkyWalking vs transmittable-thread-local
Apache SkyWalking has 24,958 GitHub stars, 6,633 forks, 41 open issues and last shipped 3 days ago. transmittable-thread-local has 8,308 stars, 1,723 forks, 57 open issues and last shipped 3 months ago. Apache SkyWalking leads on adoption by 200% (24,958 vs 8,308 stars). Apache SkyWalking is written in Java under Apache-2.0; transmittable-thread-local is written in Java under Apache-2.0. Apache SkyWalking has attracted 27% as many forks as stars, transmittable-thread-local 21%. Apache SkyWalking was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 3 topic tags (apm, dapper, distributed-tracing), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Apache SkyWalking | transmittable-thread-local | |
|---|---|---|
| GitHub stars | ★ 25K | ★ 8.3K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Java | Java |
| Last push | 2026-09-17 | 2026-06-18 |
| Forks | ⑂ 6.6K | ⑂ 1.7K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Apache SkyWalking if
- You weight community size — 25K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Java
- You value the larger contributor base for long-term maintenance
pick transmittable-thread-local if
- You want the transmittable-thread-local feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Java
- You evaluated both and transmittable-thread-local fits your workflow better
About Apache SkyWalking
Apache SkyWalking is an open source application performance monitoring (APM) system for distributed systems in cloud native architectures, built for teams that run microservices across Kubernetes and container based environments.
read the full Apache SkyWalking overview →
About transmittable-thread-local
TransmittableThreadLocal (TTL) is a small, zero dependency Java library from Alibaba that provides an enhanced InheritableThreadLocal capable of transmitting values between threads even when those threads are pooled and reused. It lives in the Java ecosystem and targets framework and middleware developers who need reliable context propagation across asynchronous execution boundaries. The library is Apache 2.0 licensed, roughly 1000 SLOC, and supports Java 6 through 21.
read the full transmittable-thread-local overview →
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Frequently asked questions
Is Apache SkyWalking or transmittable-thread-local more popular?
Apache SkyWalking has 24,958 GitHub stars and transmittable-thread-local has 8,308. Apache SkyWalking has the larger community by that measure.
Are Apache SkyWalking and transmittable-thread-local free?
Both are open source. Apache SkyWalking is licensed under Apache-2.0 and transmittable-thread-local under Apache-2.0. Neither carries a licence fee.
What is the difference between Apache SkyWalking and transmittable-thread-local?
Apache SkyWalking is written in Java and transmittable-thread-local in Java. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Apache SkyWalking or transmittable-thread-local?
Choose Apache SkyWalking if you want the larger community (24,958 stars) or its Apache-2.0 licence terms. Choose transmittable-thread-local if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.