SparkGPT vs Flyweight (2026): A Three Month ROI Guarantee or Pay Per Sale From Day One?

What Flyweight does well

Flyweight is one of the stronger sales focused agents on Shopify, and it is worth saying why before we get to the differences.

It is built to sell, not only to answer. Its homepage headline is "On brand AI chatbot for Shopify. Sells, supports & gets things done." Demo conversations show product cards with reasons for each recommendation and buttons to add products to the cart.

Merchants rate it highly. The Shopify App Store listing shows 4.8 out of 5 from 121 reviews, a Built for Shopify badge and a launch date of July 23, 2024.

It handles large and complex catalogs. The listing says Flyweight supports 1M+ products, and the free plan allows unlimited testing in Preview with up to 5,000 products. The homepage also describes quote generation, B2B workflows and handovers to a sales team.

It reaches beyond the website. Flyweight lists WhatsApp, Instagram and Messenger, plus a Ticket AI (in beta) that drafts replies inside Gorgias, Zendesk and Freshdesk.

It reports sales. Its Conversion Analytics feature tracks "orders attributed to chats with configurable attribution windows" and average order value after a chat.

It shares the risk, at least at the start. The ROI guarantee is a real step toward paying for results. Few vendors in this category put any of their fee at stake.

Flyweight pricing in October 2026

Flyweight does not publish plan prices. Its pricing page says "We tailor your AI and pricing to help you sell more and reduce support work" and asks you to book a demo.

The missing prices are not a criticism in themselves. Many tools aimed at larger stores quote each deal. It does mean you cannot compare costs until you have a proposal in hand.

How the ROI guarantee works

Flyweight's guarantee page lays out the steps. Before work starts, you and Flyweight "confirm eligibility and set out the goals, measurement, fees and guarantee terms in writing." Value can be defined as "sales contribution, support work saved or a combination." Performance is reviewed after 30 active days, and the full evaluation runs three months. If the AI meets the agreed target, you pay the fees set out in the proposal. If it does not, you "pay nothing for that evaluation." After three months you review results together, and "there is no automatic commitment."

Three details matter when you plan around it.

It is not automatic. The page says "Submitting the check or installing the app does not activate a guarantee or start a contract." Only the signed proposal does.

It is aimed at established stores. eesel's Flyweight pricing review, checked on October 22, 2026, reports that the guarantee page's timeline shows "ROI guarantee for stores over 500k," meaning stores with over $500,000 in annual revenue. The text we read on October 29 did not state a number and said eligibility is confirmed in the proposal. If your store is smaller, ask before you plan on it.

It covers three months, not the life of the contract. From month four, you pay the regular plan whatever the agent sells. The guarantee answers "does this work for us?" It does not change what triggers a charge afterward.

Flyweight is also careful in its own wording. The guarantee page says "AI assisted revenue is not the same as additional profit," and the homepage notes that its case study results are "not a guaranteed outcome." That honesty is useful, and it is a good reason to agree the measurement method in detail before you sign.

The real difference: what triggers a charge after month three

Flyweight charges for AI interactions on a plan you agree. That is a usage model. A month with many chats and few sales costs more than a month with few chats and many sales. It makes sense for a vendor that also handles support work, where every answered question has value even when nothing is bought.

SparkGPT charges for attributed sales, every month. When a visitor chats with the SparkGPT agent, the session is tagged. If that visitor places an order within 24 hours, the order is attributed to the agent, listed in the ROI dashboard and charged at 5%. Conversations that end without an order cost nothing beyond the $2.99 base. There is no three month evaluation because the pricing never stops being an evaluation.

Attribution windows: who picks the number?

Flyweight lets you pick a window of 2 hours, 1 day or one week in its analytics. That flexibility is useful for reporting, but the window changes the answer. A one week window credits the chat with orders a shopper might have placed anyway after seeing an email or an ad. eesel's review makes the same warning: the window you choose affects the result.

SparkGPT uses one fixed window: 24 hours from the chat. It is published on our pricing page and FAQ, and the same number decides the bill, so we have no reason to stretch it. If you run Flyweight's guarantee, ask which window the written criteria will use, and whether orders that also touched an email or ad are counted. Our guide on how to measure chatbot attributed revenue walks through these checks for any vendor.

What happens when a month is busy

Flyweight has not published how its paid plans behave when usage passes the agreed level, so ask for that in the proposal. SparkGPT Growth runs on prepaid credits, where 1 credit equals $1. If the balance runs out, the agent pauses rather than charging you more, and only sales draw the balance down.

The math: comparing a quote with SparkGPT

Because Flyweight quotes each store, there is no single breakeven line. You can work it out as soon as you have a number. SparkGPT is cheaper than a monthly quote when your attributed sales are below (quote minus $2.99) divided by 0.05.

These quote levels are examples for the arithmetic, not Flyweight prices. Use your own proposal.

Here is what SparkGPT costs at different sales levels:

The honest reading: for a store doing $500,000 a year, if the agent is credited with 4% of revenue, that is about $20,000 over a year, or about $1,667 a month. SparkGPT would cost about $86 a month at that level. If chat drives a far larger share of sales, a flat Flyweight plan can cost less than 5%, and its guarantee lets you test that with little risk. SparkGPT wins when sales from chat are uncertain, seasonal or still unproven, and for stores below the size Flyweight's guarantee targets. A month with no attributed sales costs $2.99, or $35.88 over a full year.

Feature comparison

Which one should you pick?

Pick Flyweight if you run an established Shopify store, you want one agent for product advice, order help, messaging channels and helpdesk drafts, you have a large or complex catalog, and you are comfortable agreeing a written proposal. If you qualify for the guarantee, the first three months carry little downside.

Pick SparkGPT if you want the bill tied to sales every month rather than only during a trial, your store is smaller or growing, you sell outside Shopify, or you want a published attribution rule you can check order by order. SparkGPT installs on any site with one line of code:

<script src="https://admin.sparkgpt.ai/widget.js" data-api-key="YOUR_WIDGET_KEY"></script>
      

For Shopify setup, see our guide to adding an AI sales agent to Shopify. If you are weighing other Shopify sales agents, read SparkGPT vs Zipchat and SparkGPT vs Alhena. For the wider picture of pricing models, see performance based AI chatbot pricing.

Frequently Asked Questions

How much does Flyweight cost in 2026?

As of October 2026, Flyweight does not publish plan prices. The Shopify app is free to install and allows unlimited testing in Preview with up to 5,000 products. Paid plans are shown inside the app or quoted after a demo, and Flyweight says they charge for AI interactions, while live chats and human takeovers are free.

What is the Flyweight ROI guarantee?

For stores Flyweight accepts, you agree goals, measurement and fees in writing, and you only pay for the first three months if the AI meets those criteria. Performance is reviewed after 30 active days. Installing the app does not activate the guarantee; only a signed proposal does. A third party review reports it targets stores with over $500,000 in annual revenue.

What happens after Flyweight's three month guarantee?

You review results with Flyweight and decide whether to continue, with no automatic commitment. If you continue, you pay the plan set out in your proposal, which is billed on AI interactions rather than on sales.

What attribution window does Flyweight use?

Its Conversion Analytics lets you choose 2 hours, 1 day or one week. Longer windows credit more orders to chat. If you rely on the guarantee, ask which window the written criteria will use.

Is SparkGPT cheaper than Flyweight?

It depends on your quote and your sales. SparkGPT is cheaper whenever monthly attributed sales are below your Flyweight quote minus $2.99, divided by 0.05. Against a $300 monthly quote, that line is $5,940 in attributed sales. In a month with no attributed sales, SparkGPT costs $2.99.

How does SparkGPT count a sale?

When a visitor chats with the SparkGPT agent, the session is tagged. An order placed within 24 hours of that chat is attributed to the agent, listed order by order in the ROI dashboard and charged at 5%. Orders outside that window, or from visitors who never chatted, are not charged.

Try it on your own store

Enter your store URL at SparkGPT and you will have a sales agent to test on your real catalog in about 10 minutes, free and with no credit card. Test it as many times as you like. When you go live, you pay $2.99 per month plus 5% of the sales it is credited with inside a 24 hour window, and nothing for chats that do not lead to an order. No proposal, no minimum store size and no three month clock. Questions? Write to hello@sparkgpt.ai.