A Salesforce org you can boot, break, and throw away.

Yours, specifically: it loads your real schema and runs your real Apex triggers, on your local machine, in about two seconds.

Fidelic is a Salesforce emulator in a 14MB Docker container. Point your tests at it instead of a real org and everything behaves the same:

• same REST responses
• same trigger side effects
• same validation errors

Except this org can also produce the failures no sandbox will let you stage:

• row locks
• rate limits
• tenant-wide throttling
• the edge cases hiding in your own logic

And it's honest about the boundary. On boot it reads your triggers and labels each one — executed, or refused, with a reason — so you never get a silently wrong answer:

docker run -p 8080:8080 -v ./mdapi:/mdapi fidelic/emulator --apex-src /mdapi
fidelic v1.0  ·  booted in 1.9s  ·  image 14 MB

classifying triggers against your org schema …
  ✓ EXECUTE     AccountTrigger          before/after insert, update
  ✓ EXECUTE     ContactTrigger          after insert
  ✗ REFUSED     CaseTrigger             EventBus.publish — not yet simulated
  ✗ REFUSED     BillingSync.trigger:88  dynamic SOQL — not in the subset

export SFEMU_FAULT_LOCK_ON_UPDATE=true   # break it on command
curl -sX PATCH $ORG/services/data/v62.0/sobjects/Account/001xx0000…
{ "errorCode": "UNABLE_TO_LOCK_ROW",
  "message": "unable to obtain exclusive access to this record" }

The failure injection alone is worth it — row locks and API limits are untestable in any real org. Fidelic makes them a config flag.

— Engineer at a major Salesforce partner