This is an independent review of GREX AI (also known as GrowthEx AI), the AI growth marketing agent built by Growth Division, a London-based startup growth marketing agency.
Similar to our reviews of GrowthHackers Projects, Truenorth.io and UpGrow, this article takes an honest look at the product: what it does, who it’s built for, how it’s priced, and how it compares to a dedicated growth marketing platform like Growth Method.
Information is correct as of June 2026. Growth Method has made every attempt to ensure the accuracy and reliability of the information provided below.
Pros
- Slack-native execution — works inside your existing team workflows
- Draws on 1,000+ past experiments run by Growth Division clients
- Handles ICP creation, channel recommendation, and experiment structuring in one flow
- Weekly automated updates on experiment velocity and North Star Metric
- Backed by an agency with 130+ startup clients and a strong track record
Cons
- Not a standalone product — GREX comes bundled with a Growth Division agency retainer
- No public self-serve pricing or sign-up
- Still in beta at time of writing
- Agency-led model means less direct team ownership of the growth process
- No native integrations with analytics tools outside of Slack
- Built on Webflow — limited platform depth compared to purpose-built SaaS
- Focused on startups; less suited to established in-house marketing teams
What is GREX AI?
According to the GrowthEx website:
“Hire GREX to run your growth marketing process. You can use the GREX AI agent to strategise, structure and execute growth experiments.”
GREX AI is the AI agent at the centre of the GrowthEx platform — a tool built by Growth Division to support their own agency delivery. Rather than being sold as a standalone SaaS product, GREX is included as part of a Growth Division client engagement. When you hire Growth Division to run your growth marketing, you get access to GREX alongside their human channel experts.
The product is positioned squarely at early-stage startups that want experiment-led growth but lack the in-house team, bandwidth, or process to do it consistently.
Who is behind GREX AI?
GREX AI is built by Growth Division, a growth marketing agency based in London (40 Bowling Green Lane, EC1R 0NE). The company was co-founded by Tom Dewhurst and Tristan Gillen, who previously grew their own startup before launching the agency.
Growth Division has worked with over 130 startups across B2B, B2C, SaaS, and tech — with a network of 80+ vetted freelance channel experts they deploy on client projects. Notable clients include Housecure and Weavr.
The agency describes its model as experiment-led:
“From growing our own startup to helping to grow over 130 since, we’ve worked out many of the classic kinks in the experimentation process — including creating our own tool that’s actually designed for ideating, tracking, and logging growth experiments, GrowthEX.”
Tom Dewhurst, Growth Division
GrowthEx (the platform) and GREX AI (the agent within it) are the technology layer built on top of Growth Division’s agency methodology.
GREX AI features
GREX AI has three core capability areas:
AI Powered Strategy
The onboarding flow uses GREX to build out Ideal Customer Personas (ICPs) and define strategic goals. Based on this input, GREX recommends 3–6 channels for the client’s go-to-market strategy. This mirrors the Bullseye Framework that Growth Division uses to prioritise acquisition channels for startups.
Build Structure
GREX sends weekly Slack updates covering experiment velocity and progress against the client’s North Star Metric. Rather than requiring the team to pull reports manually, GREX pushes structured updates into the client’s existing Slack workspace — keeping stakeholders informed without adding process overhead.
The underlying experiment board (GrowthEX) uses a kanban layout with pending, in-progress, and completed experiment states. Every experiment record captures a hypothesis, the variable being tested, the target metric, the baseline, the actual result, and a short analysis. This closely mirrors established growth experimentation best practice.
AI Agent Execution
GREX can be used directly within Slack to help ideate and prioritise experiments. According to Growth Division, the agent draws on data from over 1,000 successful experiments previously run for clients — giving it a proprietary training set that generic AI tools don’t have.
Day-to-day collaboration between the Growth Division team and clients happens over Slack, with GREX embedded in that workflow.
GREX AI pricing
GREX AI does not have public standalone pricing. It is only available as part of a Growth Division agency engagement, with pricing structured as a monthly retainer. To get access, you need to book a call with the Growth Division team via growthex.ai/contact.
This is a significant difference from self-serve growth platforms, where pricing is transparent and teams can sign up, onboard, and start running campaigns without speaking to sales.
GREX AI vs Growth Method
GREX AI and Growth Method are both positioned in the AI growth marketing space, but they serve meaningfully different use cases.
| GREX AI (GrowthEx) | Growth Method | |
|---|---|---|
| Model | Agency-bundled AI agent | Standalone SaaS platform |
| Access | Via Growth Division retainer | Self-serve sign-up |
| Pricing | Undisclosed retainer | Transparent, published pricing |
| Target user | Early-stage startups without an in-house growth team | In-house marketing teams with a growth culture |
| Execution | Human channel experts + AI agent | Marketing team + AI agents |
| Integrations | Slack | PostHog, Google Search Console, GitHub, Buffer, and more |
| Platform | Webflow + GrowthEX board | Purpose-built agentic marketing platform |
| Experiment tracking | Kanban board within GrowthEX | Full campaign lifecycle: Backlog → Planning → Live → Analysing → Complete |
| Analytics | Slack-based reports | Connected first-party data via PostHog and Search Console |
| Beta status | Yes — beta at time of writing | No — generally available |
When GREX AI might be the right choice
If you’re an early-stage startup without a dedicated marketing team and you want to outsource your growth experimentation entirely to an agency with a proven process, GREX AI within a Growth Division engagement is worth exploring. You get the AI tooling, the human experts, and the methodology packaged together.
When Growth Method might be the right choice
If you have an in-house marketing team — whether that’s a team of two or a team of twenty — and you want to build your own systematic, experiment-led growth process with full visibility into your data, Growth Method gives you a purpose-built platform to do that. You own the process, the data, and the learning. Pricing is transparent, and you can get started without speaking to sales.
Growth Method is also the better fit if you’re already using tools like PostHog, Google Search Console, or GitHub, and want a campaign management layer that connects directly to your existing stack.
Should you use GREX AI?
GREX AI is a genuinely interesting product — and the underlying agency methodology at Growth Division is well-evidenced and thoughtful. The Slack-native approach lowers friction, and access to 1,000+ past experiment learnings is a real differentiator.
The main constraint is structural: you can’t use GREX AI independently. It comes with Growth Division, which means it’s priced as an agency retainer rather than a software subscription. If that model fits your stage and budget, it’s a strong offering. If you want a product your team owns and operates directly, you’ll need to look elsewhere.
For teams ready to run their own growth experimentation process, tools like the ICE framework and a platform built around campaign tracking and first-party data will serve you better in the long run.
Looking for a GREX AI alternative? Growth Method is the agentic marketing platform for B2B teams. Plan your strategy, ship campaigns, and learn what works — all in one place.