Do I need Microsoft Word on my servers?

No. Clausul API is server-side document infrastructure, not Office automation. It runs without Word, without a desktop, and without COM.

Does it return real DOCX files?

Yes. The point of the product is Word-native artifact output. Endpoints return real .docx with native tracked changes that reviewers can open, inspect, accept, and reject in Word as usual.

Is this only for legal tech?

No, but legal, CLM, and contract workflows are an especially strong fit because tracked changes matter. Internal review systems and regulated document workflows fit equally well.

Can I use this with LLM-generated edits?

Yes — one of the clearest use cases is turning model-generated edit intent into a reviewable DOCX with real tracked changes.

Can this be deployed privately?

Private deployment interest is welcome. If VPC or on-prem matters for your use case, tell us so we can prioritise it with early design partners.

What stage is the API at?

The revision engine is in production behind the Clausul app. The public API is opening to early design partners — join the list to shape which endpoints ship first.

Clausul API · Early access

Build Word revision workflows
without Microsoft Word.

Compare DOCX files, apply edits as tracked changes, and return reviewable Word redlines from your backend. No Office automation. No desktop. Just a REST API.

Request early access See example endpoints

For legal tech, CLM, and document workflow teams that need real .docx outputs.

DOCX-native outputs

REST API

Built in Rust

Private deployment welcome

Why revision workflows are hard on the backend

Office automation is brittle

Microsoft Word was not built to be your backend. Unattended server-side Office automation is unsupported, fragile, and painful to run at scale.

Open XML is lower-level than it looks

Turning edits into valid tracked changes is more than text replacement. Revision IDs, authorship, formatting runs, and table semantics all have to line up.

Review workflows need real artifacts

Lawyers and reviewers need usable .docx outputs with native revisions, not a screenshot, a PDF, or a web viewer bolted on top.

A revision engine, not a generic document API

Compare DOCX and return tracked changes

Upload an original and revised document. Get back a reviewable DOCX with native Word revisions.

Apply edits as native revisions

Turn structured edit instructions or model-generated changes into real tracked changes inside Word documents.

Accept, reject, and inspect revisions

Programmatically work with existing redlines and revision metadata — authors, timestamps, and the structure of each change.

Transfer revisions across drafts

Apply a set of edits from one draft to another related draft, matched semantically rather than by position.

Merge revision workflows

Reconcile multiple change sets into a single next draft. Useful when several parties are working against the same agreement.

Deployment options for sensitive documents

Designed for secure environments. Private deployment options are available for selected teams as the product matures.

Planned API surface

A small set of endpoints focused on revision operations. Early access partners help shape which ships first.

POST /v1/compare Create a Word redline from two DOCX files

POST /v1/revisions/apply Apply suggested edits as native tracked changes

POST /v1/revisions/list Extract revision metadata for review workflows

POST /v1/revisions/accept Accept revisions programmatically

POST /v1/revisions/reject Reject revisions programmatically

POST /v1/revisions/transfer Carry revisions into a related draft

POST /v1/revisions/merge Reconcile multiple change sets into one output document

Built for revision-heavy document workflows

Most document APIs are broad platforms for conversion, viewing, and generic file handling. Clausul is focused on one harder problem: working with Word revisions as first-class artifacts.

High-performance Rust core

Custom DOCX engine built for predictable performance and memory efficiency under real workloads.

Revision-native DOCX engine

Designed from the ground up for tracked changes, compare, and revision operations — not retrofitted.

Artifact-grade outputs

Results open cleanly in Word with revisions intact. No viewer lock-in, no intermediate formats.

Server-side by design

Suitable for batch and workflow-driven use cases. No desktop Word in the loop.

Who it's for

Legal AI products

Turn model suggestions into real tracked changes in Word. Bridge the last mile between edit intent and an artifact a reviewer can actually negotiate against.

CLM and procurement tools

Power compare, revision review, and go-forward draft generation without building a full Word engine in-house.

Internal review systems

Programmatically process and reconcile document changes at scale — back-office review pipelines, regulated workflows, and high-volume automation.

Enterprise automation

Run revision-heavy workflows without relying on desktop Word or fragile COM automation. Private deployment options for sensitive documents.

From AI suggestion to real Word redline

LLMs can propose edits. Your product still needs to return a document reviewers can open, inspect, and negotiate. Clausul API helps bridge that last mile by turning edit intent into a native DOCX with tracked changes.

Early access

Get early access to the DOCX Revision API

We're opening access to teams building legal, contract, and document workflow products. Email us with your use case and which capabilities matter most.

Email hello@clausul.com

Tell us about compare, apply, accept/reject, transfer, merge, or private deployment needs.

Frequently asked questions

Compare documents → Transfer redline → Legal blackline → Security →

Build Word revision workflowswithout Microsoft Word.