How I Developed A $36K/Month Ecommerce Sizing Plugin

Published: June 19th, 2021
Samping Chuang
Founder, Kiwi Sizing
Kiwi Sizing
from San Francisco, CA, USA
started June 2018
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Hello! Who are you and what business did you start?

Hi, my name is Sam and I am the founder of Kiwi Sizing, which is an e-commerce plugin that helps online clothing businesses better manage their size charts and helps their customers purchase the right size.


Kiwi Sizing focuses on helping online stores with the “sizing problems”, which is a big challenge resulting in unhappy customers purchasing the wrong size because of incorrect sizing information on product pages.

The first solution we offer is a set of tools that make it very easy for businesses to create and manage to size information for all of their products. Setting up size charts sounds like an easy task, but it can get messy when you’re dealing with hundreds of different sizes from different vendors and product types. So our tool not only saves merchants time and effort to create accurate and professional-looking size charts for their customers, but we also have a ton of customization options so the styling can fit with the brands.


The next main feature is the fit recommenders which goes a step further than simply displaying sizing information but actively suggests to the customers which size we think can fit the best. We have a machine learning-driven recommender feature that can estimate the customer’s body sizes to make an educated suggestion, and we also let merchants build customized recommenders based on their logic.


Kiwi Sizing started as a Shopify plugin back in 2018 and quickly became the #1 sizing solution on the Shopify app store. We then expanded to other platforms like BigCommerce, WooCommerce, and many more. Currently, we have over 13,000 active stores worldwide, with roughly a quarter of them paying customers.

This product started just as a side project. After launching in March of 2018, it brought in around 10k by the end of the year, which was a pretty good source for my travel funds at the time and motivated me to continue investing my time in the project. It did 80k in 2019, 250k in 2020, and we are now doing over 36k/month with an average of roughly 5% MoM growth.

What's your backstory and how did you come up with the idea?

I started Kiwi Sizing while working as a software engineer in Silicon Valley. I have always enjoyed working on side projects, especially the process of designing and building products that I think could solve some real-life pain points. That’s what gets me excited and why I love building software in general.

I learned that being persistent has been one of the most important factors to Kiwi’s growth. It often took a lot longer after starting a new initiative to really see it materialized into real-world results.

So I got interested in e-commerce and specifically Shopify around mid-2017 after knowing a friend who was running a pretty successful dropshipping business selling watches from Aliexpress. So I thought, why not sell something myself too and that’s how I started a dropshipping store selling dog clothing and pet accessories. The experience as a seller had been wide-opening, to say the least, and I got to learn about merchandising, SEO, marketing, ads, building social media presence, etc.

The business brought in several thousands of sales each month, which wasn’t bad, but I quickly realized how little I enjoyed the efforts to maintain and grow sales. And there was this one specific task that had always drained my motivation just by thinking about it - setting up size charts for the pet products. To be more specific, we drop-ship all of our products from Aliexpress and this came with 2 pain points regarding sizing: each product has different sizing, and the vendor only provides sizing in centimeters.


This means for every new product I want to sell on the website, I had to manually convert each number from centimeter to inches with Google search. There were 2 size charts apps on the Shopify app store at the time, neither of which had unit conversion features. So I wasted hours adding up to 20-30 new merchandise each week. So as an engineer, this motivated me to create some kind of software that can automate this process. That was the humble beginning of Kiwi Sizing - to better convert size chart measurements between different units.

The tool was initially intended purely for the dog store I was running. And I never could have imagined how much it would have grown. But I soon realized how useful it could be for other merchants like me and shifted more of my efforts on building and scaling this plugin. And thought of more features beyond the convenience of converting units but also tackling the broader sizing problems many retail brands experience.

Take us through the process of designing, prototyping, and manufacturing your first product.

The initial idea of Kiwi Sizing was a really simple size chart app with automatic unit conversion. The customers can create size charts and provide measurements in centimeters and we will automatically convert them to inches. That’s it. However, compared to the existing solutions on the Shopify app store at the time, it was already more “advanced”. So I knew for merchants like me who were dropshipping from Chinese vendors, this would be a better solution to use. I was also confident to build a better user experience.

The project officially started around mid-December 2017 and the prototype finished in February 2018. I spent around 10-15 hours each week after work building the tool. There wasn’t much cost involved besides renting out servers

Screenshots of Kiwi Sizing v1 during initial launch. There are only 3 simple pages.


Size chart editor


Describe the process of launching the business.

The launch was quite simple through the Shopify app store. We didn’t have any other website but the Shopify app listing page. Because it wasn’t intended initially as a serious entrepreneurial attempt, I didn’t think through much of the launch strategy other than posting it in a few Facebook groups and the Shopify community forum. The installs started quite slow, averaging 2 or 3 a day, half of which usually churn within a day or two.

To improve installs, I tried a lot of things in the first month, such as optimizing the app store listing, pricing slightly lower than competitor apps, paid for an animated demo video for $500, commenting daily in Facebook groups on related posts, set up automated email for installs/uninstalls, and setting up live chat support. The daily installs eventually went up but it was hard to attribute to any specific effort. One measurably impactful thing was adding a free plan to the app, and as you can see installs suddenly ticked up from that single change. This is likely because how apps with free plan are displayed and ranked on the App Store which brought in more eyeballs.


Since launch, what has worked to attract and retain customers?

There are overall 3 main things I have focused on: delivering the best customer experience, scaling my time, and finally building defensibility for the app.

As an engineer by training, I believe the most important thing for building a successful product is the relentless focus on customer experience and delivering real values.

Obviously, marketing is a crucial component of scaling, but for a long time, I only put my focus on truly solving any sizing problems my customers have. I want to make sure the product is right and I believed the rest would follow. By being persistent on this principle for the first 2 years without spending a dime on any marketing efforts, Kiwi Sizing has grown quickly and won out from all the competitions.

One of the most important things I have done from the beginning is handling all customer inquiries myself, whether via email, live chat, or help desk. I have the Freshchat app installed on my iPhone, and I would be answering questions everywhere I went. Through direct interaction with the customers, I learned about every pain point, new feature needs, and just any potential improvements for the app. So far, I have talked to well over 5,000 clients directly over the past 3 years.

And I made it a mission from the beginning to consistently push out new updates based on customer feedback or my vision for the product. And since July 2018, I would send out a monthly newsletter for every product update. Many Shopify apps are set up in a “create & forget” manner. And that’s a real shame because without continuous improvements, you will never have an edge over other apps, and you often see partners with a handful of mediocre apps.


I also focused a lot on growing the app reviews. Not only is it a way to measure how well Kiwi Sizing is doing, but it also has a direct impact on search ranking and downloads. And being the customer support person myself plays directly into this goal. I would make sure every confused or unsatisfied customer walks away happy. This is how we can maintain a 5.0 average rating on the app store with almost 600 reviews.





Another big thing I have focused on is scaling my time since, for the first 2 years, I am the only person working on it part-time. Whatever could be automated was automated, and I relied heavily on automated email marketing. I also built a comprehensive help center with common Q&As and tutorials. Whenever I see a pattern from customer support, I would either improve the product to eliminate the source of the issue or write a help article so the support becomes more streamlined.

Finally, one crucial strategy I have focused on is building defensibility for the app. This is based on the assumption that other competitors will emerge and copy anything innovative about your product. And that has certainly been the case - when I started there were only 2 other sizing chart apps, and now there are at least over 20. And I can see many features from Kiwi Sizing being replicated in some of those apps, some even do a lousy job of directly copying email contents we send out. And that’s just the nature of competition in an open marketplace. So it’s critical to think about how defensible is the software and the conclusion I ended up with is we need to continuously make improvements, faster than any other competitors on Shopify. So the app started as a simple size chart app, then we added more advanced features like simple size recommenders, more advanced recommender, advanced size chart layout builder, size charts analytics, sizing image AI, and many more.

I also recognized the risk of being solely on the Shopify platform, and in 2020 started the process of expanding to other eCommerce platforms and hired people for SEO, ads, and content marketing. While ads turned out to be pretty ineffective for us, our effort on SEO and blogging has paid off in the past year. You can see our organic traffic and MRR revenue from non-Shopify platforms grew steadily in the past year.



Finally, one aspect that I think has helped with retaining customers and attracting new ones is our pricing. Relative to other fit finder solutions on the market which focus primarily on enterprise clients and charge thousands of dollars each month, our pricing is very friendly to SMBs which fit well with the majority of Shopify personas.

How are you doing today and what does the future look like?

Our gross margin is around 75%, with most of the cost around software hosting and hiring. We have a total of 14k active stores and add around 400 new active stores each month and revenue grows around 5% MoM. Around 25% of active shops are paying customers. On the Shopify app store, in April 2021, we had 1850 Shopify app installs (1550 install and 300 re-open) and 1400 uninstalls (650 uninstalls and 750 store closing).

On our main website, we see 3k user visits (1.6k from organic search) and an average of 2:15 time spent.

It is a risk to be dependent so much on Shopify and its app store. Currently, non-Shopify stores make up only 3% of total revenue so it is one of the big areas we are focusing on, to grow active shops on WooCommerce & BigCommerce. We are investing more in content marketing and partnerships and looking to experiment with referral and affiliate marketing. We stopped using ads after many unsuccessful attempts last year and only use retargeting ads on Google & FB.

To grow our revenue, we recognize that there are primarily the following methods: increase average spend per subscribers, increase the number of subscribers on Shopify, and expand to other platforms. So some tools we consider use will be increasing pricing on our plans or introducing other additional paid features and reducing churn. Growing Shopify subscribers is the most tricky since this has always grown organically and we don’t have much control over our visibility on the Shopify app store. One thing we are doing that could help is a partnership with other Shopify apps to increase the overall exposure to our product. Finally, we dedicate a lot of time now growing non-Shopify channels which increase our total marketable user base.

On the product side, we are looking to improve the recommender features and provide more actionable insights for the merchants.

In addition to Kiwi Sizing, I have also co-founded a new company, Shypyard. Shypyard is a new integration and automation platform for connecting different e-commerce platforms, and I am excited to bring over my past experience working with Shopify on this new venture.

Through starting the business, have you learned anything particularly helpful or advantageous?

I learned that being persistent has been one of the most important factors to Kiwi’s growth. It often took a lot longer after starting a new initiative to really see it materialized into real-world results. For example, after we started the kiwi website and put ourselves on WooCommerce and BigCommerce app stores in Feb 2020, we didn’t see much activity or installs, let alone paying customers until 4 or 5 months afterward. It almost seemed at the time, all the money and efforts putting into blog posts and ads were pointless. But now we are finally seeing the fruition of that work.

And again, relentless focus on delivering customer value is so crucial. If I did not handle all the customer support myself in the early days, I would not have had first-hand accounts of all the pain points customers are experiencing. I did all the things that wouldn’t scale well and tried to satisfy the needs of almost every single complaining customer. And this truly builds a reputation for the app, not only reflected in the reviews, but word of mouth between communities and agencies and truly made Kiwi Sizing the go-to app for most stores. I have customers telling me he owns over 10 Shopify stores and he only uses Kiwi Sizing for every one of them.

Finally, I think the most important factor of success here is honestly luck in timing. If I started the app in 2021, it certainly would not succeed. It was exactly because of the market condition in 2018, where there were only 2 unpolished sizing apps, that I could stand out and build enough reputation before other competitions joined in the race. I am forever grateful for how lucky I am to start the app back then and it also taught me that if you see an open opportunity, you need to seize it quickly because the window will close soon.

What platform/tools do you use for your business?

In terms of email marketing, I initially started with Mailchimp, but it quickly got too expensive because the cost is based on the number of contacts on the list. So we switched to SendInBlue which was a much cheaper alternative with easier-to-use UI.

For customer support, I initially tried with Zendesk and for some reason, it wasn’t the easiest to learn so I quickly moved on to Freshchat/Freshdesk combo and never switched since.

Finally, I highly recommend using tools like Fullstory to observe how your customers are really using your product and spot any places that can be confusing, especially for first-time installs. The paid plans are expensive but it comes with enough monthly free sessions where you just sample a portion of your users or focus only on certain segments (i.e. first-time users).

On the developer side, I recommend using Datadog for monitoring your services and setting up alerts. Spending time on developer efficiency and automation can really save a lot of trouble whenever an issue occurs (and they always do).

Another thing that I loved to recommend is JoinSecret deals. We have gotten a lot of sweet free credits for SendInBlue, AWS, etc.

What have been the most influential books, podcasts, or other resources?

Maybe it’s just me but I have been too focused on planning & execution for Kiwi Sizing that I didn’t really seek inspiration from other places.

Where can we go to learn more?

If you have any questions or comments, drop a comment below!

Samping Chuang, Founder of Kiwi Sizing
Pat Walls,  Founder of Starter Story
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