SnapMagic Search offers free symbols, footprints and 3D models for millions of electronic components. Its pricing page says the service is, and always will be, 100% free for designers. It exports to Cadence Allegro and OrCAD, Altium, CircuitStudio, DipTrace, Eagle, KiCad, PADS, P-CAD, PCB123, Proteus, Pulsonix and Target 3001!, and says its footprints follow IPC-7351B.
It does more than serve downloads. A checker reports on footprint manufacturability, and InstaBuild, a computer-vision tool, helps you build a missing part yourself. Plugins put the search inside Eagle, Altium, KiCad (the page says up to v5.1.10), DipTrace, Fusion, Proteus and others.
The same company also runs SnapMagic, an AI copilot built on that library. It describes adding bypass capacitors, chatting with your design in natural language and optimizing a BOM for cost or power, all inside the design tool you already use.