The GitLab CI Pipeline Cost Estimator queries the GitLab REST API v4 (/projects/{id}/pipelines and /projects/{id}/jobs) to aggregate job execution data across pipeline runs. It categorizes jobs by runner type (shared Linux, shared Windows, shared macOS, self-hosted), extracting duration and queue time metrics to calculate compute minute consumption. The skill maps usage against GitLab pricing tiers (Free, Premium, Ultimate) with their respective CI/CD minute allowances and overage rates. For self-hosted runners, it estimates infrastructure cost based on reported runner tags that map to instance types (configurable mapping for AWS, GCP, Azure instance pricing). The estimator generates monthly and per-pipeline cost breakdowns, identifies the most expensive jobs and suggests optimization targets (caching improvements, image size reduction, parallelization opportunities). It supports cross-project aggregation for group-level cost reporting and exports data in CSV format for finance team consumption.