Your Always-On Marketing Brain

How We Built a CustomGPT Marketing Brain in Under 15 Minutes

We’ve been building "Marketing Brain" CustomGPTs for clients—and they’re game-changing. Think of it as a brand-trained assistant that helps your team refine headlines, tighten CTAs, and keep your tone consistent across campaigns. Built in under 15 minutes. Lives in ChatGPT forever. Zero meetings needed.

Watch the video below for a full walkthrough of exactly how we build them and how to use them.

Why SaaS Teams Are Building CustomGPTs

SaaS marketers live in messy docs and Slack threads trying to align around brand voice, value props, and what makes their product resonate with users. Multiply that by copy across email, ads, in-app, landing pages—and things get inconsistent, fast.

Enter: your brand-trained CustomGPT.
We’ve started creating these for clients as an "always-on marketing brain"—a GPT trained on your:

• Brand voice & tone guidelines
• ICP details and messaging frameworks
• Email campaigns & sequences
• Landing pages and ads
• Core value props, positioning docs, and blog content

Once trained, it’s like having a brand strategist on-call—inside ChatGPT.

The Build: A Step-by-Step Breakdown

Watch the [video above] to see it in real time, but here’s the high-level process we walk through:

1. Scrape and Organize the Brand’s Core Assets

Before starting the GPT creation process, we collect everything that defines the brand:

• Website copy
• Landing pages
• 15–20 recent emails
• Ads, social captions, long-form content

We organize and format these for easy upload.

2. Train the GPT Using ChatGPT’s Custom Builder

We jump into OpenAI’s GPT builder and prompt it like so:

"You are a marketing brain trained on [Brand X]. Your job is to review, improve, and advise on content in the brand’s voice and messaging style."

From there, we upload the files, including grouped batches like:

• website-assets.pdf
• email-sequence-1.docx
• ads-and-headlines.docx

The GPT ingests everything and begins to develop context.

3. Reinforce Brand Voice + Vocabulary

We then ask the GPT to list brand-specific terms, create a voice profile, and help define tone. We paste those back into the system prompt to refine its guidance engine.

Example:

• Voice: Confident, expert, concise
• Key phrases: "growth loops," "trial-to-paid," "data-driven lifecycle"

4. Test & Iterate with Real Prompts

Once loaded, we give it prompts like:

"I’m writing a landing page for a new feature launch. What headline, subhead, and value props should I use?"

And the GPT responds with tight, on-brand suggestions—anchored in real messaging from the uploads.

What It’s Good For (and What It’s Not)

These CustomGPTs shine in review and optimization use cases:

• Fixing tone and phrasing
• Tweaking headlines and CTAs
• Rewriting sections to be more aligned
• Ensuring consistency across channels

But they’re not great for:

• Complex thought-leadership or original strategy
• Deep insight posts that require human nuance
• Full campaign creation from scratch

Think of it like: Copywriter’s assistant, not a copywriter replacement.

Why This Matters for SaaS Marketing Teams

When we rolled these out for clients, the benefits were immediate:

1. Consistency Without the Policing

No more Slack debates about style guides. Everyone’s aligned—even freelancers.

2. Content Review in Minutes

Quickly test CTAs, tweak subject lines, and gut-check tone—without looping in 4 stakeholders.

3. Scale Messaging Across Channels

Email, ads, in-app, sales decks. The GPT keeps messaging sharp across every touchpoint.

Want One? We’ll Build It For You—Free

We’re building a few of these for select SaaS marketing teams.

If your team:

• Sends lots of emails
• Struggles with keeping messaging consistent
• Wants to speed up marketing production

Contact us and let’s build your marketing brain.