Three high-impact growth experiments you can launch in days (not weeks) 

When it comes to growth, speed matters. The faster you can test ideas, the quicker you learn what works (and what doesn’t). But traditionally, experimenting with new strategies—like referral programs, self-service tools, or direct mail campaigns—requires heavy engineering involvement, slowing everything down.

That’s where marketing automation and integration-friendly platforms come in. By creatively leveraging APIs and automation tools, you can launch powerful experiments without waiting on a development backlog.

At ikaros, we’ve run countless growth experiments using low-code solutions and automation tools like Customer.io—helping teams validate ideas in days rather than weeks. These initiatives go beyond simple marketing automation—they are strategic experiments that test and validate new growth flywheels, customer engagement strategies, and operational efficiencies. Traditionally, implementing these kinds of experiments would require weeks of engineering work and significant investment, often with uncertain outcomes. But not anymore! Here are three high-impact experiments you can implement with minimal engineering effort.

Referral programs are a proven growth lever, but they’re often deprioritized due to development constraints. However, you don’t need a custom-built system to test one—just a smart combination of existing tools.

For one of our clients in the insurance space, we created a fully functional referral program in less than a day using Stripe and Customer.io. With a simple API setup, we automated the entire process—eliminating the need for a custom-built system. This approach makes it possible for non-technical teams to launch and manage referral programs without heavy engineering support.

The premise was simple: when customers make their first purchase, they receive a unique referral code. Friends and family can use this code at checkout for a 25% discount, and the referrer gets their own 25% discount code for each successful referral.

To make this work, we created two separate coupons in Stripe: one for new customers using the referral code and another for referrers to redeem their discount. Stripe’s terminology can be confusing—"coupons" define the discount rules, while "promotion codes" are the codes customers enter at checkout. In Stripe’s UI, we set up the referral codes so each one could be used multiple times, but each new customer could only redeem a code once. The referrer, however, received a unique reward code for each successful referral, limited to a single use.

Next, we set up three campaigns in Customer.io:

• Referral code generation: Triggered when a new customer signs up and completes a purchase. A webhook calls Stripe’s API to generate a unique promo code, which is then stored on the customer’s profile in Customer.io. We also save the customer’s cio_id in the promotion code’s metadata field in Stripe—this is crucial for tracking referrals. The customer then receives an email with their referral code and program details.
• Referrer reward creation: This is triggered when a referral code is used at checkout. A webhook fetches the original referrer’s cio_id from Stripe’s metadata, allowing us to identify the referrer without a complex database lookup. Using this ID, we generate a new discount code for the referrer and trigger an event in Customer.io.
• Referrer notification: The event sent from the previous step triggers a third campaign in Customer.io, which automatically emails the referrer their personal discount code for their next purchase.

This experiment remains in operation today and showcases the power of rapid testing. Traditionally, developing a referral program from scratch would have required significant engineering resources. By leveraging automation, we were able to launch, test, and iterate quickly, without a heavy investment.

High-friction booking processes can kill conversions. One of our clients in the home service industry relied on manual appointment scheduling—forcing customers to call their local branch. As part of ikaros' growth strategy work, we identified the need for a more seamless booking process and proposed a self-service system to increase efficiency and customer engagement. To prove its value, we implemented an MVP using Customer.io and Webflow without touching the company’s legacy backend.

The first step was syncing customer data from the CRM into Customer.io. Previously, appointment reminders were sent manually just once per month—a process that burdened the marketing team and hurt retention. We replaced this with an automated campaign that sent timely reminders, ensuring customers were notified when their yearly recurring appointment was due.

To remove the friction of phone-based appointment scheduling, we introduced personalized booking links that directed customers to a dedicated Webflow-hosted booking page on a separate subdomain. This approach offered several advantages:

• Marketing controlled the booking experience, without relying on support from the engineering team.
• Content updates were seamless—copy and imagery could be adjusted directly within Webflow.
• Faster iterations were now possible, thanks to Webflow’s no-code platform.

To personalize the experience, we embedded customer information directly into our URL parameters. This allowed us to pre-populate the booking form with known details like name and contact information. Additionally, we appended a unique customer ID to the URL, ensuring a persistent link to the Customer.io profile. This approach meant that customers didn't have to manually enter details we already had, reducing friction and improving conversions.

One challenge we faced was the lack of real-time technician availability data. To work around this, we designed a system where form submissions trigger a Customer.io campaign that dynamically sends booking requests to the appropriate branch based on the customer’s location.

Here’s how it worked:

1. When a customer submits the form, the event captures their unique ID, preferred date, and time for the appointment.
2. The campaign matches the request to the correct branch using Customer.io’s Collections.
3. An automated email is sent to the branch staff with the request details.
4. The branch staff confirms availability manually or follows up with the customer to propose alternative slots.

This approach significantly improved conversion rates, with appointment bookings increasing by 54%. It also reduced the marketing and customer service teams' manual workload, saving an estimated $50,000 in labor costs. Importantly, we were also able to implement this in parallel with the client's legacy system, which saved lots of time and resources.

For businesses with offline customers, digital engagement isn’t always an option. The same client in the home service industry needed a way to reach homeowners by mail—without a manual, time-consuming process.

To address this, we integrated Customer.io with ClickSend, a service that automates direct mail via API. If no phone number or email address is available, a Customer.io campaign triggers a webhook when a new home is registered in the CRM, sending homeowner details to ClickSend. ClickSend then prints and mails a letter containing activation instructions, ensuring that homeowners are reached even when digital contact information is unavailable.

However, ClickSend’s API does not support dynamic letter customization, limiting our ability to personalize messaging and track customer engagement effectively. To overcome this, ikaros developed a utility app called Hermes, a lightweight API that accepts Word documents with merge fields and generates fully personalized PDFs on demand.

A key innovation was including a personalized QR code in each letter, with the recipient’s details stored as URL parameters. When homeowners scan the QR code, they are directed to a pre-filled activation form, eliminating manual entry and increasing conversion rates.

The final campaign flow works as follows:

1. A Customer.io webhook sends letter details to Hermes.
2. Hermes returns a link to a fully personalized PDF
3. Customer.io forwards the PDF link and recipient details to ClickSend via webhook, which prints and mails the letter.

Here’s what the letter looks like:

This solution automated an otherwise manual outreach process while ensuring a high level of personalization. The inclusion of a trackable QR code provided real-time insights into homeowner engagement and streamlined the activation process by minimizing conversion barriers.

These examples demonstrate how Ikaros leverages Customer.io for rapid, high-impact experimentation. If you’re looking to apply a similar approach, here are our top recommendations:

1. Understanding APIs unlocks new growth possibilities. Knowing how to work with APIs allows marketers to automate complex workflows, trigger external actions, and connect tools like Stripe and ClickSend seamlessly.
2. Customer.io is more than an email tool—it’s a customer engagement platform. From triggering external processes to dynamically routing data based on real-time events, it's a powerful platform for reaching your customers.
3. Leverage low/no-code tools whenever possible. Platforms like Webflow, Stripe, and ClickSend can be used without much or any development support.
4. Work fast with cloud-based solutions. SaaS tools allow teams to test and iterate quickly without waiting on internal IT approvals or infrastructure changes.

Happy experimenting!