Are you looking for a convenient and hassle-free way to create, edit, or modify STL files for your 3D printing or modeling projects? Look no further! We've curated a list of the best free online STL editors that enable you to work on your 3D designs without the need to download any software.

1. Tinkercad: Tinkercad is a popular online 3D design and modeling tool that allows users to create and modify STL files with ease. Its intuitive interface and drag-and-drop functionality make it perfect for beginners and hobbyists.

2. FreeCAD: FreeCAD is a powerful open-source parametric 3D modeler that includes a module for editing STL files. It offers a wide range of features for advanced users and supports a variety of file formats.

3. MeshMixer: MeshMixer is a versatile 3D modeling tool that lets you edit and sculpt STL files with its user-friendly interface. It also provides advanced features like auto-repair and analysis tools for 3D printing.

4. 3D Slash: 3D Slash is a unique online 3D modeling tool that uses a cuboid-based approach to create and manipulate 3D designs. It's ideal for creating voxel-based models and supports exporting to STL format.

5. SelfCAD: SelfCAD is an all-in-one online 3D modeling software that includes a variety of tools for creating, sculpting, and editing 3D designs. Its user-friendly interface and powerful features make it suitable for both beginners and professionals.

These free online STL editors offer a range of features and tools to accommodate different skill levels and project requirements. Whether you're a beginner looking to create simple designs or an experienced designer working on complex projects, these tools provide the flexibility and convenience of online editing without the need to install any software. Explore these options and start bringing your 3D design ideas to life today!