Create PDF annotation layers in Flutter

What is an Instant layer?

An Instant layer represents a set of document changes, such as annotations, bookmarks, form fields, and digital signatures. Users with write access can edit the layer, while those with read access can only view it.

What it’s best for

Layers are ideal for independent review workflows where multiple parties need to annotate or modify the same document separately. Common use cases include:

• Student-teacher workflows — Students annotate the same PDF independently, while teachers provide private feedback on each student’s layer
• Multi-reviewer processes — Different reviewers provide feedback without seeing each other’s comments

Benefits

• Low storage cost — Layers on the same document identifier share access to the same source file, eliminating the need to reupload, while keeping each layer’s content isolated
• Minimal bandwidth — Adding layers doesn’t require transferring the document again
• Scalable — It’s inexpensive to add multiple layers on clients and servers

For more information about layers, refer to the Instant layers guide.