Using .DOCX Templates to Automate Contracts: How We Built Contractize with .NET, Angular, and Formize API

When building a SaaS tool for legal contract automation, we explored a wide range of options — from HTML-to-PDF pipelines to custom templating engines. In the end, the best solution turned out to be something surprisingly old-school: .docx templates.

In this post, I’ll explain how we used Microsoft Word templates, ASP.NET Core, Angular, and Formize API to create Contractize.app — a modern platform for generating legally valid contracts with minimal developer effort.

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🚀 Why We Built Contractize

Our goal was simple:

Let startups, HR teams, and freelancers create legally sound contracts in seconds — without needing legal help or Word editing.

We wanted to:

• Empower non-developers (legal, HR, founders) to manage templates

• Allow users to generate contracts via a simple form

• Produce polished PDFs with zero manual formatting

This meant choosing a tech stack that was both developer-friendly and legal-team-friendly.

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🛠 The Tech Stack

Here’s what we built the platform with:

• Frontend: Angular

• Backend: ASP.NET Core (C#)

• Document Engine: .docx templates + Formize API

• Storage: Azure Blob Storage

• Output: Auto-generated PDFs delivered via link or email

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📄 Why .docx Templates (and Not HTML or JSON)?

You might ask: Why not use HTML + PDF generators like Puppeteer or jsPDF?

We tried those. And ran into issues:

• HTML PDFs often broke with complex layouts

• Custom JSON-to-PDF pipelines were hard to maintain

• Legal teams couldn't edit the output without dev help

.docx templates solved all of that:

• ✅ Created and edited directly in Microsoft Word

• ✅ Rich formatting: tables, styles, sections

• ✅ Human-readable placeholders like {{clientName}}

• ✅ Editable by legal teams without touching the code

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🔌 How Our Document Generation Works

Here’s the workflow behind Contractize:

1. A user fills a contract form on the Angular frontend

2. The backend builds a data payload

3. A request is sent to Formize.com:

{
  "templateId": "contract-template.docx",
  "data": {
    "clientName": "Acme Corp",
    "startDate": "2025-05-27",
    "termLength": "12 months"
  }
}

4. Formize returns a URL to a filled PDF

5. We display the contract to the user or send it by email

It’s fast, stable, and scales well.

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🧠 What We Learned

• .docx templates are version-controlled in Git

• Legal teams edit templates without dev involvement

• Minimal code changes when contract layout updates

• Formize handles all the parsing/rendering logic

• Backend stays lean and focused

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📈 Scaling the Platform

Today, Contractize automates:

• NDAs

• Employment offers

• Service agreements

• Partnership contracts

We support:

• Language toggles (e.g. EN/DE templates)

• Dynamic clauses (arbitration, term duration)

• Template sets for different industries

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🧭 What’s Next

We’re exploring:

• E-signature integration (DocuSign, HelloSign)

• No-code clause toggles in templates

• Smart template suggestions via AI

• Analytics on clause usage trends

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🔍 TL;DR

If you’re building a platform that involves dynamic document creation:

• .docx is still unbeatable for legal and professional documents

• Formize API makes it easy to integrate with modern stacks

• You don’t need to reinvent templating logic or maintain PDF rendering code

You can check out our platform here:
👉 https://contractize.app

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🙋 Let’s Chat

Have you built something similar?
Got questions about integrating .docx in your app?
I’d love to hear from you — drop a comment or connect!