B4OS — Structure

Program schedule

B4OS lasts between 5 and 8 months depending on contribution pace. Each phase has clear objectives and continuous review.

Weeks 1–4 Phase 1

Deep fundamentals

Intensive study of the Bitcoin protocol: consensus, scripting, UTXO model, mempool, and Bitcoin Core internals. Mentor-guided source code reading.

Weeks 5–8 Phase 2

First contributions

Review of open issues, bug reports and documentation. Your first PR to an open source ecosystem project. Weekly code review with an active contributor.

Weeks 9–16 Phase 3

Technical contributions

Work on real features: Bitcoin Core, LDK, LND, CLN or layer 2 projects. Intensive 1:1 mentorship. Pull requests reviewed by ecosystem maintainers.

Weeks 17–24 Phase 4

Closing project

Documented significant contribution, community presentation and alumni network. Final evaluation and certification. Transition toward an active contributor grant.

Cohorts

Cohort Q3 2025

July — February 2026

Applications open

Apply to this cohort

Cohort Q1 2026

January — August 2026

Coming soon

Reserve your spot in the next cohort

Applications for Q3 2025 are open. Limited to 8 participants per cohort.

Apply now View benefits →