Tinify.dev - An image API with honest results

Solo builder. I run image infrastructure for my own projects and kept being annoyed by two things in existing services: APIs that report "savings" while quietly returning a bigger file, and error responses that change shape between endpoints. So Tinify.dev's API has a short contract: compression never returns a file larger than the input (you get optimized: false and your original bytes back - resize and crop report size changes plainly, and format conversion can legitimately grow a file), one error envelope everywhere (code, message, request_id), required idempotency keys, batch up to 200 files. Kotlin/Spring + sharp on a Hetzner box. The launch hook: there's now an MCP server (npx -y @tinify-dev/mcp), so an AI agent can compress, resize, crop, or convert local images mid-task - output goes next to the input, never overwriting the source. Plus a GitHub Action that compresses images in PRs and posts a savings table. Free: web tools with no ads or signup; API at 500 operations/month with no card. Paid from $9/mo (2,000 ops) and $29/mo (10,000). Limits, stated plainly: 40 MB / 50 MP per image, results expire after two hours, one machine, no SLA on the free tier. Not affiliated with Tinify B.V. (TinyPNG). Questions welcome - I'll be here all day.