AntiSemVer

Semantic Versioning answers:

"What changed?"

AntiSemVer answers:

"How dangerous is this release?"

Instead of describing compatibility, it describes expected disruption.

Developers should stop assuming version numbers increase monotonically or indicate feature growth. The version is a communication tool about operational risk.

AntiSemVer systematically inverts the conventions developers expect from Semantic Versioning:

Example: 8.1.97 means Randomness = high, Instability = low, Confidence = extremely high.

First number — Randomness

Instead of increasing every release, it is generated from a deterministic hash of the Git tree.

Git hash → SHA256
Take first byte
mod 10
Result: 0–9

Therefore:

release A    2.5.91
next release 8.5.92
next release 1.6.90

Version numbers appear to jump randomly.

Useful because identical source trees always produce identical first numbers.

Second number — Instability

Higher means less stable.

0 = boring
9 = experimental

Unlike SemVer, adding a feature might decrease this number if the implementation became more mature.

Examples:

5.8.90
  ↓
5.3.91
  ↓
5.1.92

New releases can look "older."

Third number — Confidence

Starts at 100.

Every known bug subtracts points.

Example:

100
 ↓
 96
 ↓
 84
 ↓
 79

Fixing bugs makes this number increase again.

Therefore versions may go:

3.4.92
   ↓
3.4.96

without changing anything else.

There isn't one.

Two releases cannot be ordered by version number.

Instead each release has a timestamp.

This intentionally breaks 1.2.4 > 1.2.3 because that assumption causes many package manager problems.

Compatibility is never encoded.

Instead every release contains:

Compatible with:
  2026-04
  2026-06

or:

Compatible with API profile "Hydra"

Compatibility becomes explicit metadata instead of inferred from numbers.

Nothing special happens.

Breaking changes can happen at:

1.0.100
   ↓
1.0.99

or:

8.8.88
   ↓
2.3.97

Consumers are expected to read release notes or compatibility declarations.

Instead of bumping a major version, releases receive a Chaos Level.

This is subjective but intentionally human-readable.

8.7.94
Chaos Level: Medium
Confidence: 94%
Instability: 7
Compatible Profiles:
    HTTP-v3
    API 2026-Q2
Known Issues: 6

Rather than:

>=2.3.0

dependencies are written like:

Confidence >= 90
Instability <= 3
Compatible profile = API-2026

This is actually more expressive than SemVer.

Despite breaking almost every SemVer convention, AntiSemVer still communicates valuable operational information:

In other words, AntiSemVer replaces a change-oriented versioning scheme with a deployment-oriented one. It deliberately discards nearly every assumption of Semantic Versioning while remaining coherent enough that tooling and users could still make informed decisions about whether to adopt a release.