JetBrains added Eco Mode to Junie, cutting model cost per task by about half in internal tests

On October 28, 2026, JetBrains introduced Eco Mode in Junie, which lets the chosen model plan a task and hands implementation and testing to a cheaper model. JetBrains reported 48% and 57% lower average model cost per task in two internal benchmarks.

Archive entry: this covers an event from October 28, 2026, and we published it on November 8, 2026. The details come from sources dated at the time and may have changed since.

On October 28, 2026, JetBrains introduced Eco Mode in Junie, as described in a JetBrains blog post by Helena Klause. Eco Mode let the model the user selected plan a task and passed the rest of the work to a cheaper model.

What changed

The selected model investigated the coding task and created a plan, then a lower-cost model handled implementation and testing.
During planning, the selected model could read and search code but not change it.
In two internal benchmarks, Eco Mode reduced average model cost per task by 48% and 57%.
Average resolve rates changed by less than one percentage point.
Eco Mode was on by default for supported model-and-effort configurations.

What it meant for builders

Junie users paying for premium models could roughly halve their cost per task without switching models. The model they had chosen still did the investigating and planning, and only implementation and testing moved to a lower-cost model, which JetBrains said left average resolve rates nearly unchanged.

Availability

Eco Mode was available to JetBrains Air EAP users in IntelliJ IDEA 2026.3 Beta and in 2026.2 versions of JetBrains IDEs, with other IDE betas to follow. It was generally available in the Junie CLI starting with version 26.10.20.

Sources

Junie Eco Mode (JetBrains, October 28, 2026, official)

Written with AI assistance, strictly from the sources listed above. Before it went live, automated checks verified its dates, sources and every language edition.