PHP developer plans, codes and maintains the server side of web products built in PHP. First they study specifications with stakeholders, break features into user stories and design database schemas: tables, indexes, relations. During implementation they follow PSR conventions, use Composer for dependencies, write object-oriented classes, traits and interfaces, and expose functionality through REST or GraphQL endpoints. Security is routine: filtering input, escaping output, validating tokens, preventing SQL injection, XSS and CSRF. They integrate third-party APIs such as payment processors, CRM, mail services, caching layers or message queues, and orchestrate them by writing tests in PHPUnit, running static analysers and configuring CI pipelines. Performance duties include profiling with Xdebug, tuning OPcache, optimizing queries and adding Redis or Memcached. They also build presentation with templating engines or output JSON for front-end frameworks. Finally they document code, review merge requests, refactor legacy projects, manage Docker images, orchestrate deployments and monitor production logs.