Software Engineering
Updated Sat, 24 Sep 2022 13:42:53 GMT

What is the significance of reaching major version 1.0.0?

I have seen many open source projects being labelled as "not production ready" because they have not reached a major version e.g. 1.0.0 using semver.

What is the significance of reaching this milestone? Is there a criteria that must be met for a piece of software to be considered a major version? Or is it arbitrarily decided by the authors of the software?


There is a special difference between 0.0.0 and 1.0.0. Let's dig into the Semantic Versioning standards. The following rules label these numbers as x.y.z:

When x is 0

Chaos rules.

  1. Major version zero (0.y.z) is for initial development. Anything MAY change at any time. The public API SHOULD NOT be considered stable.

Semantic Versioning 2.0.0

When x is greater than 0

Things start meaning things.

  1. Version 1.0.0 defines the public API. The way in which the version number is incremented after this release is dependent on this public API and how it changes.

  2. Patch version Z (x.y.Z | x > 0) MUST be incremented if only backwards compatible bug fixes are introduced. A bug fix is defined as an internal change that fixes incorrect behavior.

  3. Minor version Y (x.Y.z | x > 0) MUST be incremented if new, backwards compatible functionality is introduced to the public API. It MUST be incremented if any public API functionality is marked as deprecated. It MAY be incremented if substantial new functionality or improvements are introduced within the private code. It MAY include patch level changes. Patch version MUST be reset to 0 when minor version is incremented.

  4. Major version X (X.y.z | X > 0) MUST be incremented if any backwards incompatible changes are introduced to the public API. It MAY also include minor and patch level changes. Patch and minor versions MUST be reset to 0 when major version is incremented.

Semantic Versioning 2.0.0

So yes there is a magical difference between x going from 0 to 1 vs going from 1 to 2. People are funny about zero.

Of course many projects that still use 0 as their major are stable. The point is you weren't promised that stability by this version number.

Not everything with a version number uses semantic versioning and may not follow these rules. Read the documentation before making assumptions.


Web 2.0, Super Bowl XXX, Star Wars Episode V. And just to round out this gigantic landscape I give you: Mostly Harmless "The fifth book in the increasingly inaccurately named Hitchhikers Trilogy".

Sorry if I gave the impression that semantic versioning was universal.

Comments (5)

  • +0 – And of course, you have the famous example of Oracle which started at version 2.3 for marketing reasons, because who is going to trust version 1.x of enterprise software? — Aug 24, 2022 at 23:27  
  • +2 – Note that this is for software which follow semver, which is a requirement for modules which provide an API in some environments (so users of the module can now when it is safe to upgrade or not), and is also followed by other software, but there is no requirement for a standalone application with no API to follow it. — Aug 25, 2022 at 08:45  
  • +7 – Not everyone uses SemVer, though. SemVer is a good start, a good idea, but it is also not perfect and has problems, and while advocates of SemVer seem to think it is the holy grail, there are reasons not to use, and many project in fact don't. An answer claiming that only SemVer exists misses a gigantic part of the landscape out there. — Aug 25, 2022 at 09:36  
  • +6 – @Polygnome semver was explicitly mentioned in the question, so I think this answer is fine. — Aug 25, 2022 at 10:08  
  • +1 – @raznagul it does say "e.g. 1.0.0 using semver" - it's not clear whether semver is part of the example or part of the question — Aug 26, 2022 at 14:36  

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