Overview
Codex can now generate redlined Word documents with real Track Changes markup. Upload your contract alongside a rules file or describe the required edits in a prompt, and Codex identifies the relevant clauses and applies the requested changes as tracked edits directly in the document. The generated .docx includes insertions, deletions, and replacements that can be accepted or rejected in Microsoft Word or any compatible editor.
How to Use Codex Redline
Click on Codex from the left-hand navigation bar.
Click the + icon in the prompt bar and select Upload Files.
Upload your contract file (.docx) and your rules file (.txt or .docx). Both files will appear as attachments in the prompt bar.
Type your instruction in plain language. For example: "Check redlines if any according to the rules" or "Review this contract against the rules file and generate a redlined Word document with Track Changes."
Click Send.
Codex will analyse both files, identify clauses that do not align with the rules, and apply the required changes as tracked edits.
Reviewing the Output
Once complete, Codex displays:
Redlined document ready — a summary of all changes applied, including what was changed and why, referencing the specific rule each edit is based on.
Changes in this turn — a numbered list of every replacement made, showing the original text (Was), the updated text (Now), and the rule that triggered the change (Why).
Live document preview — the right panel shows the contract in OnlyOffice with Track Changes visible. Deleted text appears with strikethrough and new text appears underlined, making every edit visible at a glance.
Downloading the Redlined Document
Once you are satisfied with the changes, click the download icon on the artifact card at the bottom of the Codex chat. The file downloads as a .docx with all Track Changes intact, ready to open in Microsoft Word where you can accept or reject each edit individually.
You can also click Open to preview the full document in the OnlyOffice panel before downloading.
Refining the Document
You can continue the conversation in the same Codex thread to refine the document further. Type a follow-up instruction and Codex will apply additional changes to the same document, keeping the redlined version up to date across turns.
Example Prompts
"Review this contract against the rules file and generate a redlined Word document with Track Changes."
"Check redlines if any according to the rules."
"Apply track changes to align this NDA with our standard playbook."
"Redline the termination and liability clauses based on the attached guidelines."
Conclusion
Codex Redline brings contract markup directly into your workflow. Instead of manually comparing and editing contracts clause by clause, you can upload your files, describe what needs to change, and receive a fully redlined Word document in seconds, with every edit sourced back to the rule that triggered it.