Custom GPTAI assistantcompany docstutorial

Custom GPT for Company Docs: How to Build Your Own AI Assistant

Cortexiva Team•February 3, 2026•10 min read

What Is a Custom GPT for Company Docs?

A Custom GPT is an AI assistant trained on your specific documentation. Instead of getting generic answers from ChatGPT, you get answers grounded in your company's actual policies, procedures, and knowledge.

Imagine asking "What's our parental leave policy?" and getting an accurate answer that quotes your employee handbook—not a generic response about typical parental leave policies.

This guide covers two approaches:

  • OpenAI's Custom GPTs - Quick setup, limited features
  • Dedicated knowledge bot platforms - More features, better for teams

    • Option 1: Building with OpenAI Custom GPTs

    Step-by-Step Setup

    Prerequisites:

  • ChatGPT Plus subscription ($20/month)
  • Your company documents in PDF or text format
  • 15-30 minutes

    • Step 1: Access GPT Builder

  • Go to chat.openai.com
  • Click "Explore GPTs" in the sidebar
  • Click "Create" in the top right

    • Step 2: Configure Your GPT

    Name it something descriptive:

  • "Acme HR Assistant"
  • "Engineering Wiki Bot"
  • "Company Policy Guide"

    • Write clear instructions:

    ```

    You are an assistant that answers questions about [Company Name] policies and procedures.

    Only answer questions using the uploaded documents.

    If the answer isn't in the documents, say "I don't have information about that in my knowledge base."

    Always cite which document your answer comes from.

    ```

    Step 3: Upload Your Documents

  • Click "Upload files" in the Knowledge section
  • Add PDFs, text files, or documents
  • Maximum ~20 files, 512MB total

    • Step 4: Test and Refine

    Ask common questions:

  • "What's our PTO policy?"
  • "How do I submit expenses?"
  • "What's the remote work policy?"

    • Adjust instructions if answers aren't accurate.

    Step 5: Share

  • Click "Save" and choose visibility
  • "Only me" - Just you
  • "Anyone with a link" - Shareable (but they need ChatGPT account)
  • "Everyone" - Public in GPT store

    • Limitations of Custom GPTs for Teams

    Custom GPTs work for personal use, but have significant limitations for team deployment:

    Everyone needs ChatGPT Plus

  • $20/user/month
  • 50 users = $1,000/month just for access

    • No access controls

  • Can't restrict to specific email domains
  • Can't limit what different users can see
  • No audit trail of who asked what

    • No analytics

  • Can't see what questions are asked
  • Can't identify documentation gaps
  • Can't measure usage or ROI

    • Manual document updates

  • When docs change, you re-upload manually
  • No auto-sync with Notion, Drive, etc.
  • Easy to get out of date

    • Inconsistent citations

  • Sometimes cites sources, sometimes doesn't
  • No timestamps on information
  • Hard to verify accuracy

    • US data only

  • All data processed in US
  • GDPR compliance requires extra work
  • May not meet legal requirements

    • Option 2: Dedicated Knowledge Bot Platforms

    For team use, dedicated platforms address the limitations of Custom GPTs:

    Key Differences

    FeatureCustom GPTKnowledge Bot PlatformSetup cost$20/user/monthPer-bot pricingAccess controlNoneEmail/domain restrictionsAnalyticsNoneFull usage trackingSource citationsInconsistentAlways with timestampsDocument syncManualAuto-refresh availableData locationUS onlyEU availableTeam managementNoneAdmin controls

    When to Use Each

    Use Custom GPTs when:

  • You're the only user
  • Testing a concept before investing
  • Documentation is non-sensitive
  • You already pay for ChatGPT Plus

    • Use a dedicated platform when:

  • Multiple team members need access
  • Data sensitivity requires compliance
  • You need analytics and insights
  • Professional deployment matters

    • Building with a Knowledge Bot Platform

    Let's walk through setup with Cortexiva as an example:

    Step 1: Create Your Bot (2 minutes)

  • Sign up at cortexiva.com
  • Click "Create Bot"
  • Name it (e.g., "HR Knowledge Base")
  • Select department/category
  • Choose tone (professional, friendly, concise)

    • Step 2: Add Knowledge Sources (3 minutes)

    For PDFs:

  • Click "Add Source"
  • Drag and drop files
  • Wait for processing (30-60 seconds per doc)

    • For Notion pages:

  • Click "Add Source" → "URL"
  • Paste your Notion page URL
  • System fetches and indexes content

    • For web pages:

  • Same process as Notion
  • Works with most public web content

    • Step 3: Configure Settings (2 minutes)

    System prompt:

    ```

    You are a helpful HR assistant for [Company].

    Answer questions about company policies, benefits, and procedures.

    Be concise and professional.

    ```

    Confidence threshold:

    How confident should the bot be before answering? Higher = fewer but more accurate answers.

    Fallback message:

    What to say when the bot doesn't know:

    "I don't have information about that. For HR questions, please contact hr@company.com"

    Step 4: Set Access Controls

    Public: Anyone with the link can use

    Domain-restricted: Only @company.com emails

    Invite-only: Specific email addresses

    Step 5: Deploy and Share

  • Copy the shareable link
  • Pin in Slack/Teams channels
  • Add to company intranet
  • Include in onboarding materials

    • Advanced: Building Your Own from Scratch

    If you have engineering resources and specific requirements, you can build custom:

    Tech Stack

    Vector Database (for semantic search):

  • Pinecone
  • Weaviate (self-hosted option)
  • Qdrant
  • Chroma (open source)

    • Document Processing:

  • LangChain
  • LlamaIndex
  • Custom pipeline

    • LLM:

  • OpenAI GPT-4
  • Anthropic Claude
  • Google Gemini
  • Self-hosted Llama

    • Backend:

  • Python (most common)
  • Node.js
  • Go

    • Frontend:

  • React
  • Vue
  • Plain HTML/CSS

    • Realistic Timeline and Cost

    Initial development: 2-4 months

    Team required: 1-2 engineers

    Ongoing maintenance: 20-40 hours/month

    Infrastructure cost: $500-5,000/month depending on scale

    When Building Makes Sense

  • You need deep customization
  • You have specific security requirements
  • Scale makes per-seat pricing prohibitive
  • You have engineering bandwidth
  • It's a core competency investment

    • When Building Doesn't Make Sense

  • You need something deployed this week
  • You don't have AI/ML expertise
  • Your requirements are standard
  • Engineering time is better spent elsewhere

    • Best Practices for Any Approach

    Start with high-impact documents:

  • Employee handbook
  • Benefits guide
  • Common policies
  • Onboarding materials

    • Test with real questions:

  • Use actual questions from your Slack history
  • Verify answers against source documents
  • Note where answers are wrong or incomplete

    • Plan for maintenance:

  • Documents change
  • Set review schedules
  • Monitor for outdated information

    • Communicate clearly:

  • Tell people the bot exists
  • Explain what it knows (and doesn't)
  • Make the link easy to find

    • Measure success:

  • Questions answered
  • Time saved
  • User satisfaction
  • Reduction in repeat questions

    • Conclusion

    You have three paths to a Custom GPT for company docs:

  • OpenAI Custom GPTs: Fast and free (with ChatGPT Plus), but limited for teams
  • Knowledge bot platforms: Best balance of features and ease of use
  • Build your own: Maximum control, maximum investment

    • For most teams, a dedicated platform offers the best ROI: deploy in hours, not months, with features built for team use.

    Try Cortexiva free - Build a custom GPT for your company docs in 5 minutes.

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