Jenkins

The open-source automation server that most of the industry's CI ran on, and much of it still does.

Older than most of this list, still deployed everywhere.

What it is sold for

Running builds and deployments on your own infrastructure.

The rest of ci, cd and infrastructure, alphabetically. Sharing a category is a filing decision, not a relationship.

Abstra

Automation for finance operations, built as workflows rather than as spreadsheets.
Ansible

Agentless configuration management over SSH, with playbooks in YAML and no daemon on the target.
AWS Step Functions

Orchestrates AWS services as a state machine, so retries and failure branches are configuration rather than code.
Buildstash

Artifact and release management for teams shipping binaries: mobile, desktop, games, XR and embedded.
Camunda

Process orchestration for long-running work that spans people, systems and now agents, with the model as the executable.
CircleCI

A hosted CI platform, one of the older ones, now marketing itself around validating machine-written changes.
Datadog

Metrics, logs, traces and a great deal more in one platform. The default answer for large-scale monitoring, and priced like it.
DeployHQ

Deploys from a git host to servers with build steps, zero-downtime releases and one-click rollback.

ImranTools[Jenkins]