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mirai vs webmockr

A side-by-side editorial comparison of mirai and webmockr — release velocity, themes, recent moves, and the top alternatives to consider.

mirai vs webmockr: at a glance

Featuremiraiwebmockr
SectorAnalyticsAnalytics
Velocity score2.50.0
Sparks · 30d00
Top themesparallel-computing, async, backpressure, shinyhttp-mocking, testing, httr2, ropensci
Last editorial update6h ago1h ago
WebsiteVisit →Visit →

What is mirai?

mirai removed its dispatcher process and added memory backpressure to the queue.

The async evaluation framework releases roughly monthly and moves fast at the architecture level. In 2.7.0 the dispatcher stopped being a separate process and became a thread, after its loop had already been rewritten in C inside nanonext one release earlier. The same release added an opt-in memory budget for queued task payloads and try_mirai(), which returns NULL immediately rather than blocking when that budget is exhausted.

Read the full mirai trajectory →

What is webmockr?

The stubbing library added httr2 support, then spent a year cutting itself free of everything else

webmockr intercepts HTTP requests in R tests and returns stubbed responses, and since 1.0.0 it covers all three clients that matter — httr, httr2 and crul. The releases through 2025 have been about shedding dependencies: internal R6 classes unexported in 2.1.0, crul demoted from Imports to Suggests in the same release, and the mutual dependency with vcr severed in 2.2.0. The package now installs and runs without pulling in the rest of the rOpenSci HTTP stack.

Read the full webmockr trajectory →

mirai vs webmockr: editorial side-by-side

M
mirai
ANALYTICS
2.5

mirai removed its dispatcher process and added memory backpressure to the queue.

◆ Current state

The async evaluation framework releases roughly monthly and moves fast at the architecture level. In 2.7.0 the dispatcher stopped being a separate process and became a thread, after its loop had already been rewritten in C inside nanonext one release earlier. The same release added an opt-in memory budget for queued task payloads and try_mirai(), which returns NULL immediately rather than blocking when that budget is exhausted.

◆ Where it's heading

Two threads of work run together: cutting overhead out of the task path — thread-based dispatcher, in-process transport for synchronous daemons, lower per-element dispatch cost in mirai_map() — and making the framework safe to embed in an event loop, where blocking the host R thread is not acceptable. Deployment reach is growing too, with http_config() launching remote daemons over HTTP APIs and auto-configuring for Posit Workbench. Each release pins a minimum nanonext version, so the two packages advance as one unit.

◆ Prediction

With backpressure in place but opt-in, the open question these notes leave is whether a default memory budget arrives; continued overhead reduction and Shiny-facing non-blocking paths are the safer bet.

W
webmockr
ANALYTICS
0.0

The stubbing library added httr2 support, then spent a year cutting itself free of everything else

◆ Current state

webmockr intercepts HTTP requests in R tests and returns stubbed responses, and since 1.0.0 it covers all three clients that matter — httr, httr2 and crul. The releases through 2025 have been about shedding dependencies: internal R6 classes unexported in 2.1.0, crul demoted from Imports to Suggests in the same release, and the mutual dependency with vcr severed in 2.2.0. The package now installs and runs without pulling in the rest of the rOpenSci HTTP stack.

◆ Where it's heading

Two arcs run in sequence. The first is coverage — multiple queued responses in 0.7.0, basic auth mocking, async through crul, then httr2 — building out what can be stubbed. The second, starting with 2.0.0, is correctness and independence: stubs are now deleted if an error occurs mid-construction rather than lingering half-built, partial matching arrives for bodies and queries, and the dependency graph is pruned release by release. The 2.2.0 split from vcr landed within a minute of crul's release taking mocking control into its own clients.

◆ Prediction

RequestPattern is documented as still exported in 2.1.0 but slated for removal, so the next major release is where that lands. Expect continued dependency pruning rather than new client support — the three clients that exist are already covered.

Alternatives to mirai and webmockr

Other Analytics products tracked by Sparkpulse, ranked by recent ship velocity. Each card links to a full editorial trajectory and lets you pivot into a head-to-head comparison with either mirai or webmockr.

See all mirai alternatives → · See all webmockr alternatives →

Recent activity from mirai and webmockr

Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.

  1. 25d agomiraiMap collection and daemon lifecycle fixes
  2. 2mo agomiraiAgent skill ships in-package; HTTP headers take over auth
  3. 3mo agomiraiDispatcher becomes a thread, and the queue gains a memory budget
  4. 5mo agomiraiParallel RNG seeding leaves experimental status
  5. 6mo agomiraiRemote daemons over HTTP, and a C dispatcher loop
  6. 8mo agomiraiTelemetry span timing and daemon-switch fix
  7. 1y agowebmockrvcr dependency severed
  8. 1y agowebmockrInternal classes unexported; crul becomes an optional dependency
  9. 1y agowebmockrFailed stub construction cleans up; partial matching extends to bodies and queries
  10. 2y agowebmockrhttr2 joins httr and crul as a supported client
  11. 3y agowebmockrQueued responses, body matching and integer status codes fixed
  12. 3y agowebmockrRegex URI matching fixed

Frequently asked questions

What is the difference between mirai and webmockr?

They serve adjacent needs but don't currently overlap on shipped themes. mirai is currently shipping more aggressively (velocity 2.5 vs 0.0), with 0 editorial sparks in the last 30 days against 0. See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.

Is mirai better than webmockr?

Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. mirai is currently shipping more aggressively (velocity 2.5 vs 0.0), with 0 editorial sparks in the last 30 days against 0. For your specific use case, the alternatives sections above list other Analytics products to evaluate alongside.

What are the best alternatives to mirai?

Top mirai alternatives in Analytics are ranked by recent ship velocity. Browse the "mirai alternatives" section above for the current picks, or visit /alternatives/mirai for the full list with editorial commentary on each.

What are the best alternatives to webmockr?

Top webmockr alternatives in Analytics are ranked by recent ship velocity. Browse the "webmockr alternatives" section above for the current picks, or visit /alternatives/webmockr for the full list with editorial commentary on each.