COMTiles is a novel geospatial data format designed to efficiently store and manage map tiles in a cloud-native environment. It addresses the limitations of existing formats like Mapbox MBTiles and OGC GeoPackage, which are not optimized for cloud deployment. COMTiles introduces a streamable index that stores tile offsets and sizes, enabling efficient retrieval from cloud object storage using HTTP range requests. The format leverages metadata based on the OGC "Two Dimensional Tile Matrix Set" specification to support various tile coordinate systems. One key feature of COMTiles is its simplified deployment workflow. Users can upload a single COMTiles file to a cloud object storage service like AWS S3, eliminating the need for complex tile server setups. This ease of deployment reduces hosting costs significantly, making it accessible even to non-GIS experts. In tests, a planet-scale OpenStreetMap tileset with 90 GB in size was deployed on Cloudflare R2 storage, incurring hosting costs of only $1.35 per month. COMTiles also offers a better user experience by reducing latency and improving tile access efficiency. Its batching approach minimizes the number of HTTP requests, especially when displaying maps in fullscreen mode. In performance tests against another cloud-optimized tile archive solution (PMTiles), COMTiles demonstrated faster decoding, reduced data transfer, and faster initial map load times. While PMTiles had a smaller index size, the additional storage cost of COMTiles proved to be negligible, given the affordability of cloud storage. Overall, COMTiles streamlines large tileset deployment, reduces storage costs, and maintains a user-friendly experience, making it a promising format for managing and deploying map tiles in cloud-native environments.