In 30 seconds
- Make only what's needed, just when it's needed.
- Pull work based on demand, not push based on forecasts.
- A pillar of the Toyota Production System.
Origins
Taiichi Ohno developed just-in-time at Toyota as one of the two pillars of the Toyota Production System, alongside jidoka. Kanban cards signalled when to produce more parts.
Pull, not push
In a pull system, downstream steps signal when they need more work. Nothing is produced to sit in inventory. In software, a Kanban board with WIP limits creates pull.
JIT in agile
- Refine backlog items just before they're needed
- Detailed planning only for the next sprint
- Decide at the last responsible moment
Myth vs reality
Myth · JIT means no inventory at all.
Reality · It means minimal, purposeful inventory.
Myth · JIT is fragile.
Reality · It needs stable flow; buffers can be planned.
Myth · It only applies to manufacturing.
Reality · Agile planning applies JIT to information.
FAQ
What's the link to Kanban?
Kanban cards were the original JIT signal.
Can JIT backfire?
Yes, if supply is unreliable; that's why flow stability matters.
What's just-in-time requirements?
Detailing requirements only when they're about to be built.