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v…MIT LICENSEOPEN SOURCEgithub.com/hephbuild/heph
FIG.01 / 06+ OPEN SOURCE
Open-source build system

Build once.
Trust the cache.

heph hashes every input, runs each action in a sandbox, and content-addresses the output. Same inputs, byte-identical artifacts — every machine, every time.

byte-identical
FIG.01 — BUILD GRAPH
cachebuiltedited
0 cached · 0 built
FIG.02 / 06 · The system

Built on six guarantees

+ WHY HEPH
01

└─ Content-addressed

Every artifact is keyed by the hash of its inputs. A matching digest is a cache hit, not a rebuild.

02

└─ Sandboxed actions

Each action runs isolated with its declared inputs only. No leaked state, no “works on my machine.”

03

└─ Minimal DAG

heph rebuilds only the targets whose exact sources or dependencies changed — never the world.

04

└─ Remote cache

Share a content-addressed cache across the team and CI. One build populates it; everyone hits it.

05

└─ Parallel by default

Independent targets run concurrently across every core.

06

└─ Orchestrator

Not only builds — tests, tasks and pipelines run in one isolated, deterministic graph.

FIG.03 / 06 · The pipeline

One deterministic pass

SOURCE ──▶ ARTIFACT
deterministic · hermetic · cached
SOURCE
inputs
──▶
HASH
xxh3
──▶
SANDBOX
hermetic
──▶
CACHE
outputs
──▶
ARTIFACT
✓ cached
SAME INPUTS → SAME OUTPUT, BYTE FOR BYTE
98.6%
median cache hit
12×
faster CI, typical
0
flaky builds
1,284
targets / repo