TheAlgorithms/PHP: a categorized shelf of algorithms for one language

A README that opens with its own limitations

Most repositories of this kind lead with what they offer. This one leads with what it is not. The README describes the project as a library or framework written in PHP providing algorithms and data structures for various computational tasks, then immediately adds a section titled for education and states that the implementations are examples and may be less efficient than the implementations in the PHP standard library.

That disclaimer is the most useful sentence in the whole README, and it is unusual to see it this high up. It removes the most common misreading of a repository called TheAlgorithms, which is that it is a dependency you wire into a project. It is not. There are no tagged releases, there is no usage documentation showing how to install and call anything, and the project description is the flat phrase all algorithms implemented in PHP. What you get when you arrive is a well-organised set of files to read.

The remaining README content is short by design and mostly procedural. It points contributors at a contribution guide and asks them to read it first, points readers at a separate directory file for navigation rather than trying to serve as an index itself, and names two community channels, a Discord and a Gitter room, with an invitation to ask questions. There is a Gitpod badge at the top, which tells you the project expects contributions from people who do not have a PHP environment set up locally.

All of this amounts to a repository with a deliberately small amount of ceremony. That is a design choice, and given what the repository is for, it is the right one. An index in the README would go stale the moment a directory was added. A generated file does not.

Twelve directories are the entire taxonomy

The tree is the substance of this repository. There is no source file at the root, no library entry point, and no directory of tests at the level where a package would put one. What there is is a dozen top-level directories that classify the contents by problem domain, plus the supporting files:

Ciphers/
Conversions/
DataStructures/
Graphs/
Maths/
NeuralNetworks/
Searches/
Sorting/
Strings/
Utils/
DIRECTORY.md
composer.json
phpcs.xml.dist
tests/

This classification is the part worth studying, because it is stricter than most people expect. Graphs and Searches are separate directories rather than one, which means a breadth-first search belongs with graph traversal rather than with search algorithms. Strings and Conversions are separate, which keeps number base conversion and unit conversion from sitting next to string manipulation. Maths stands alone from DataStructures. NeuralNetworks has its own top-level directory, which is a choice that says something about how the collection treats machine learning relative to the rest of the discipline.

Note what is not there. There is no Algorithms directory, no DynamicProgramming directory, no BitManipulation directory. That absence is a signal about how the taxonomy was drawn: categories are created by convention across the family of language repositories rather than designed top down for PHP, and only categories with enough accumulated content get their own directory. Disagreements about where a given algorithm belongs are resolved by the same contribution process that adds the algorithm, which is why the categories drift over time.

The Ciphers and NeuralNetworks directories are the two most likely to be mistaken for something other than what they are. Ciphers here means classical and modern textbook ciphers, not applied cryptography. NeuralNetworks means implementations of the architectures, not a framework or a training pipeline. Neither directory should be reached for in production work.

One part of a family, which changes how you read it

The organisation is TheAlgorithms, and the repository is one language branch of it. The GitHub topics include hacktoberfest, which is a strong hint about how this repository grew: bulk contributions arrive during a seasonal event, are filtered by a review process, and end up as many small pull requests. A repository that receives hundreds of contributions a year through that route develops conventions quickly, because the alternative is a review queue nobody can process.

The consequences of being a language branch are concrete. Consistency with the sibling repositories is not optional, so a new implementation has to match conventions that were set by contributors working in other languages and never explained in this README. The directory taxonomy is shared, which is why the classification feels slightly arbitrary from the inside. And the contribution guide, which the README points at twice, is where those conventions are actually written down.

For a reader this is a feature in one sense and a cost in another. The cost is that the PHP branch cannot be judged on its own terms: a directory that exists here also exists in the Java branch, a Rust branch, and dozens more, and the PHP branch inherits decisions made for a collection it does not control. The feature is that you can compare implementations across languages in a consistent layout, which is genuinely useful if you are trying to understand what a bubble sort looks like in a language whose sorting conventions you know badly.

Fork numbers make the same point. With 586 forks against 2,651 stars, the fork ratio here is far higher than in the projects most people read forks as a signal about. Those forks are not people sending pull requests. They are people taking the PHP branch and reshaping it, which is what you would expect from a repository whose value is its contents rather than its interface.

What the supporting files tell you about quality control

Three root-level files describe how the code is kept consistent, and together they paint a picture of a repository with real but lightweight conventions. There is a Composer manifest, which in a project with no releases and no library entry point is almost certainly there for autoloading and dev dependencies rather than for distribution. There is a coding standards configuration for the PHP_CodeSniffer tool, named with the .dist suffix so a local override can sit beside it without being committed.

The tests directory is the third, and its presence matters more than its size would suggest. It means implementations are expected to be verifiable, and that verification is wired into the contribution flow rather than left to the reader. For an educational repository that is the difference between a folder of plausible code and a folder of code somebody checked. It also means the review burden per contribution is real, which is the main reason the project can afford to accept a large volume of them.

What none of this gives you is a performance baseline. There is no benchmark suite in the tree, no comparison against the standard library, and no statement anywhere about which implementations are efficient enough for real use beyond the general disclaimer. So the quality story here is correctness-oriented and educational: the code should work and should be idiomatic enough to read, not fast. If you need the fast version, PHP ships one in many cases and the README is right to point you there first.

Maintenance signals are consistent with that. The repository was last pushed on 2026-08-10, has nine open issues, is MIT licensed, and sits on a default branch named master rather than main. The branch name is a small fossil of the family's age, and it is the kind of detail that dates a project more reliably than its star count does.

Who this is actually for

It is worth being explicit about the audience, because the star count invites a reading this repository does not support. Three groups fit. The first is someone learning algorithms who wants to see a familiar problem solved in PHP specifically, in the language they are working in, with conventions that match that community rather than a textbook's pseudocode.

The second is someone porting knowledge across languages. If you know what a topological sort looks like and want to see how it reads when written by someone who works in PHP, a consistent cross-language layout is a shortcut past the parts you already know. This is also where the education disclaimer matters least, because reading correctness is the entire goal.

The third is a person building a portfolio. Adding a well-organised, tested, style-conformant implementation to a widely starred repository is a contribution that is legible to a reviewer without any further context, and the hacktoberfest topic suggests the review pipeline is set up to handle exactly that volume. Whether that is a good use of an afternoon is a separate question, but the friction is genuinely low.

Who it is not for is anyone reaching for it to solve a production problem. The disclaimer says so, the absence of releases says so, and the structure says so. There is nothing to install, no stability promise, and no support commitment behind the directory names. Treating it as a reference to read rather than a dependency to declare is the whole mental model, and once you have it the repository does exactly what it claims.

Editorial conclusion

TheAlgorithms/PHP is best understood as a reading repository rather than a library. It ships no releases and no package documentation, it hands navigation off to a generated directory file, and it tells readers directly that the implementations may be less efficient than what ships with PHP. That framing is honest and it is what makes the 2,651 stars reasonable: nobody is installing this, people are reading it and adding to it. The directory taxonomy is the real contribution, since it forces a consistent classification across a language where the standard library already covers a lot of ground. For production work the honest advice is to use the standard library first and read this second. For learning, or for a contribution portfolio, the value is real and the barrier to adding a well-organised implementation is low.

Frequently asked questions

Official sources

1. Issues
2. License: MIT
3. README
4. TheAlgorithms/PHP on GitHub