SB3 editor

About This Tool

The SB3 editor provides programmatic access to Scratch 3 SB3 projects by validating and editing the project.json and related JSON structures inside the SB3 zip. It accepts a .sb3 file, unpacks, and exposes the project graph, sprites, scripts, and metadata for inspection and modification. The tool preserves asset references and ensures the resulting file remains a valid Scratch 3.0 project.
Core operations include structural validation against the Scratch 3 schema, read-only analysis, and controlled edits to allowed fields such as project metadata, sprite properties, and script blocks represented in JSON. Edits are applied with integrity checks to prevent broken JSON or invalid block trees. Upon completion, the tool reassembles the zip into a new SB3 file.
Target users are educators, curriculum developers, and researchers who need reproducible Scratch projects, content auditing, or migration between classroom environments. Typical use cases include preparing a demo project for a lesson, exporting a sanitized version for sharing, or aligning projects to classroom templates while preserving assets.
Unique value lies in offline, deterministic processing with strict JSON-level validation and export of a compliant SB3; it enables version-controlled edits, automated checks, and safe batch operations without executing Scratch code or relying on the Scratch runtime.

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