BlenDiff

See what changed between two versions of a .blend file.

BlenDiff compares scenes, not bytes. It reads the file through Blender's own Python API, so instead of "these files differ" you get "this chair moved, that material was rewired, this mesh was subdivided". Save a snapshot whenever you reach a point worth keeping, then compare any two of them, or compare one against whatever is open now.

Snapshots live in a .blendiff file next to your .blend, so a project folder holds those two files and nothing else.

Detecting a geometry edit

The blackboard was reshaped in edit mode. BlenDiff picks up the new topology, the changed vertex positions and the UVs, without storing a copy of the mesh.

Comparing against a snapshot

Object level changes, property by property. The chair here was renamed, hidden from renders, moved and rotated, and BlenDiff tracks the rename as a rename rather than reporting an unrelated deletion and addition.

Merging two versions

Give BlenDiff a common starting point and two versions that grew apart. It applies the changes that do not overlap and asks you about the ones that do. Apply Merge stays disabled until nothing is left undecided.

What it compares

• Objects: position, rotation, scale, parenting and custom properties
• Visibility: viewport and render switches, selectability, display mode, and the per-ray flags that decide whether something casts a shadow or shows up in reflections
• Meshes: a moved vertex, a subdivided face or a re-unwrap, caught by comparing content digests rather than storing the geometry
• Materials: node graphs, node by node, including rewired links and image names
• Armatures: bone hierarchy, rest pose, roll, bone collections, pose transforms and bone constraints, so a reparented finger or a rewired IK chain is visible
• Modifiers and constraints: the whole stack, in order, with per setting detail
• Geometry nodes: the node group on a modifier and every input it exposes, by the name you see in the panel rather than an internal socket number
• Shape keys: each key's value, mute, slider range and interpolation, plus whether the shape itself was sculpted
• Animation: keyframe counts, frame ranges, interpolation, drivers and NLA tracks
• Scene settings: render engine, resolution, sampling, output format, colour management, world background, cameras and lights
• Collections: which objects belong where, and whether a collection is hidden, excluded or set to holdout
• Curves, text, empties and the rest: the settings that shape them, such as a curve's bevel and extrude or a text object's contents and spacing

Renames are tracked properly. Objects carry a hidden id, so renaming Cube to Body_LOW stays one modified object with its other changes intact.

Snapshots also record which of these they captured. If an old snapshot predates a feature, that part is reported as not compared instead of being diffed, so upgrading BlenDiff never fills your first diff with changes nobody made.

Installation

Blender 4.2 and newer

Edit > Preferences > Get Extensions, search for BlenDiff, click Install. Updates arrive on their own.

Blender 3.6 to 4.1

Download the latest blendiff-<version>.zip from Releases and install it with Edit > Preferences > Add-ons > Install from Disk.

Either way, the panel appears in the 3D viewport sidebar. Press N and look for the BlenDiff tab.

Using it

1. Save your .blend file. BlenDiff needs somewhere to put its history.
2. Press Save Snapshot and give it a name, something like "before rigging". If you would rather not remember, turn on Snapshot on save in the add-on preferences and one is taken every time you save. Those are pruned to a limit you set; the ones you take by hand are kept.
3. Carry on working.
4. Open Snapshot History and press play next to any snapshot to compare it against the current scene. To compare two saved snapshots to each other instead, pick them in Compare Two Snapshots and press Compare.
5. To go back, press the restore button beside a snapshot. It writes that snapshot's values over the scene in one undo step, and tells you what it could not account for. It never creates or deletes objects, so anything made since the snapshot is left alone.
6. Export HTML Report writes a single self contained page you can send to someone who does not have the file open.

For a merge, take a snapshot of the common starting point, then one of each version that grew from it, and pick all three in the Three-Way Merge panel.

What merge writes back

BlenDiff only claims to apply what it can actually apply. Anything it cannot write back is shown as read only, so it never asks you to choose a value it would then discard.

Also available as a Python library

BlenDiff installs from PyPI as a plain Python package, with no Blender required, for comparing snapshots in scripts or in continuous integration:

pip install blendiff

See docs/development.md for the command line tool and the Python API, and docs/architecture.md for how the code is put together.

License

GPL-3.0-or-later. See LICENSE.

BlenDiff is licensed under the GNU General Public License v3 or later because Blender's Extensions Platform requires it: anything using the bpy API is treated as a derivative of Blender, which is itself GPL. The pip package and the Blender addon ship the same code under the same terms.