The most scalable and reliable MQTT broker for AI, IoT, IIoT and connected vehicles
C-Rank Grade: S (Elite) - 72/100
External PR Merge Rate: 68%
Response Time: 2h
First Timer Success: 60%
emqx/emqx has a recorded first-timer success rate of 60.0%. Repositories ranked S typically provide actionable feedback during code reviews and actively nurture new community contributors.
Maintainers in emqx/emqx respond to incoming external pull requests in approximately 2.4 hours on average. Keeping PRs focused on single tasks and ensuring tests pass helps maintainers review faster.
The C-Rank™ system evaluates GitHub projects on a 0–100 scale using real data: PR merge rates, review turnaround time, active maintainer presence, and first-time contributor success. A score of 71.9 places emqx/emqx in the S tier.
The external contributor pull request merge rate for emqx/emqx is 68.4%, based on public PR activity from non-core contributors.
emqx/emqx does not currently have active "good first issue" tags indexed, but accepts external contributions through standard GitHub issue tracking.
Strict review standards in emqx/emqx. Ensure PR scope matches issue requirements closely before requesting review.
Discussions in emqx/emqx focus heavily on practical implementation feedback, code formatting standards, and issue reproduction details.
Unlinked PRs without issue context and changes that fail automated test suites face the highest review friction.
Average Response Latency
Tracks hours until a maintainer leaves a review, comment, or PR response.
External Acceptance Rate
Percentage of community pull requests successfully merged into main.
First PR Conversion
Rate at which developers submitting their first repository PR succeed.
Show contributors that your repository actively reviews and merges external pull requests.
[](https://getmerged.abhishekco.de/emqx/emqx?utm_source=github&utm_medium=badge)
Historical health & responsiveness evolution
External PR acceptance
First PR success rate
50% receive response in
90% receive response in
Maintainer review activity heatmap & prime window prediction
Calculating local time...
Calculating local time...
Detected: UTC
Maintainers are most responsive around 14:00 UTC (14:00 UTC in your timezone). Recommended submission window is Tuesday - Thursday from 12:00 to 16:00 UTC (12:00 - 16:00 UTC local).
Maintainer Strategy: Maintainer Sweet Spot: PRs under 150 lines merge in ~4 hours (85% approval). Large PRs (>500 lines) take ~11 hours (31% approval). Keep your diff compact for rapid review.
What happened? An MQTT 5 client connected over WebSocket (ws:// / wss://) with Session Expiry Interval = 0 (or absent, which means 0), and Will Delay Interval > 0 never gets its will message published when the connection is closed abnormally (TCP reset / process killed, i.e. no DISCONNECT packet and no WebSocket close frame). The same client over plain TCP (mqtt:// / mqtts://) gets the will message published immediately, as expected. Observed matrix (client killed with SIGKILL, subscriber waiting on the will topic): transport proto Session Expiry Will Delay will received ws 3.1.1 - - immediately ws 5 30 10 after 10 s ws 5 30 0 immediately ws 5 0 10 never ws 5 1 10 after 1 s ws 5 absent 10 never ws 5 0 0 immediately tcp 5 0 10 immediately tcp 5 absent 10 immediately Debug log for the failing case (ws, expiry 0, delay 10): msg: websocket_closed, reason: {error,sock_closed} msg: maybe_publish_will_msg_other_delay, reason: sock_closed msg: websocket_terminated
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When evaluating whether to contribute to emqx/emqx, response velocity and maintainer engagement are crucial. GetMerged continuously tracks pull request trajectories, first-comment latency, and code review rounds to help developers avoid submitting pull requests to backlogged repositories.
Currently, maintainers of emqx/emqx acknowledge new external contributions in approximately 2 hours. Out of all submitted pull requests from non-core authors in the last 180-day window, 68.4% were successfully merged into the primary branch.
emqx/emqx has a recorded first-timer success rate of 60.0%. Repositories ranked Elite typically provide actionable feedback during code reviews and actively nurture new community contributors.
The initial maintainer response time averages ~2 hours. Keeping PRs scoped to single concerns and ensuring CI checks succeed will optimize review turnaround.
The C-Rank™ index scores repositories on a 0 to 100 scale using an objective formula: external PR merge rates, initial response speed, active maintainer count, and first-time contributor retention. A score of 71.9 places emqx/emqx in the Elite tier.
The external pull request merge rate is 68.4%. GetMerged isolates non-core community contributions so external developers get an accurate benchmark of PR acceptance probability.
emqx/emqx does not have open beginner labels indexed currently, but external PRs for bugs and documentation improvements are evaluated via normal issue triage.
All metrics displayed for emqx/emqx are automatically retrieved via the public GitHub API and recalculated daily. Insider pull requests submitted by repository owners or organization members are excluded from merge rate calculations to preserve objective external contributor statistics.