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  1. TESIGN / RADAR
  2. Breakscale

Breakscale

System-design simulator for learners

WHO USES ITBackend job seekers · Mentors of junior engineers · Service operators

Use in the browser

Browser system-design simulator: build a topology, load it until it breaks, see why

★ 1.2kDaily star increases over 14 days. Hollow bars mean no data. The last day may be partial.2026-09-03 no data2026-09-04 +52026-09-05 +22026-09-06 no data2026-09-07 no data2026-09-08 no data2026-09-09 no data2026-09-10 no data2026-09-11 no data2026-09-12 no data2026-09-13 no data2026-09-14 no data2026-09-15 no data2026-09-16 no datalargest one-day increase in the 14 days+5last 14 days · stars per dayhollow = no data

1,156 stars · checked on GitHub GitHub check 30 h late · no 7-day star increase observed (GH Archive) (as of )

RANKS EDUCATION #6

BACK CATALOG

Breakscale's Retry Storm example: a top bar reading 100 requests per second offered, goodput 0/s, errors 100% and 118/s dropped, a canvas with Client → API Server → Database boxes showing the database 99.9% busy, and a handwritten-style explanation below
Breakscale's Retry Storm example: a top bar reading 100 requests per second offered, goodput 0/s, errors 100% and 118/s dropped, a canvas with Client → API Server → Database boxes showing the database 99.9% busy, and a handwritten-style explanation below

TESIGN TAKE

Instead of telling you to add a cache, it shows the numbers collapsing until you understand why.

TRY

AT A GLANCE

LICENSE
MIT
USAGE
Use, change and redistribute, commercially too. Keep the notice.
LANGUAGE
TypeScript
PLATFORM
web
ACTIVITY
last commit 2 days ago () · no releases
COMMUNITY
14 contributors · 14 open issues (incl. PRs) · made by: an individual
SOURCES
GitHub
OPEN SOURCE
YES
FIRST SEEN
CATEGORY
EDUCATION · DEV TOOLS

A summary, not legal advice.

WHY IT MATTERS

System design is usually taught with static diagrams and rules of thumb like 'add a cache', which never explain why p99 latency falls off a cliff past 80 percent utilisation. Breakscale runs a discrete-event simulator in the browser, with finite server slots, gamma-distributed service times and measured percentiles, so that, in the README's account of the Retry Storm example, 100 offered requests per second become 348 hitting a database that is 99.9% busy while goodput is zero. It ships 33 components and 23 examples: sixteen teaching scenarios and seven reconstructions of Netflix, Spotify, Discord and other real architectures.

BUILD FROM THIS

  • The engine in src/sim has no React or DOM dependency, so you can drive Engine from a script to generate teaching material or capacity-planning experiments, and add components or examples that model your own architecture.

WHO IT'S FOR

Backend job seekers
load-test the classic system-design interview topologies yourself
Mentors of junior engineers
demonstrate retry storms, circuit breakers and sharding live
Service operators
thought experiments that reproduce an outage

START IN 5 MINUTES

# # No install: https://breakscale.tech
# git clone https://github.com/xevrion/breakscale.git
# cd breakscale
# bun install
# bun dev   # http://localhost:5173

CAVEATS

  • Licence MIT (the bundled Caveat font is separately under SIL OFL 1.1). Runs entirely in the browser with no account or telemetry, and a design stays on your machine unless you create a share link.
  • Running locally requires Bun. The seven real-company architectures are teaching diagrams reconstructed from published material, not insider knowledge, as the README states.
  • Workers IO (YC F26) is listed as title sponsor.

RECEIPT

FIRST SEEN
AT SOURCE
KEPT
CREATED → FIRST SEEN
21d
SOURCES
GitHub
◌ BACK CATALOG
Reconstructed from archive data, not a live discovery.

The same facts in machine-readable form — View as Markdown · JSON

SIMILAR TOOLS

Up to five from EDUCATION by ★ total: edited entries first, then repository cards; this entry is highlighted. Drawn from the same stored snapshot as the rankings — a comparison, not a recommendation.

IMAGENAME★ TOTAL▲ 7dLICENSEPLATFORMLAST PUSH
Breakscale's Retry Storm example: a top bar reading 100 requests per second offered, goodput 0/s, errors 100% and 118/s dropped, a canvas with Client → API Server → Database boxes showing the database 99.9% busy, and a handwritten-style explanation below
BreakscaleSystem-design simulator for learnersTHIS ENTRY★ 1.2k—MITpermissiveweb
novuhq/novuCARD★ 40k—Licence unconfirmedunconfirmed—
ankitects/ankiCARD★ 30.5k▲ +22Licence unconfirmedunconfirmed—
zyronon/typewordsCARD★ 10k▲ +15GPL-3.0copyleft—
we-promise/sureCARD★ 9.9k▲ +8AGPL-3.0copyleft—

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TIMELINE

  1. Repository created
  2. FIRST SEEN BY TESIGN ◌ BACK CATALOG