Flex Upsell Cart Auto Discount vs sK Cart Filler: Free Shipping
Two Shopify apps, side by side: detected stores, momentum, reviews, plans, listed features and who runs each. Store counts as of Nov 9, 2026 for Flex Upsell Cart Auto Discount, Oct 13, 2026 for sK Cart Filler.
The short answer
- Both list a free plan. Paid plans start at $19/month for Flex Upsell Cart Auto Discount and $6.99/month for sK Cart Filler.
- sK Cart Filler lists 7 features Flex Upsell Cart Auto Discount’s listing doesn’t mention, including Cart upsell, Free shipping, Gift wrap.
Head to head
- United States
- Australia
- Canada
Momentum
New reviews each month
Review pace is the clearest public read on how fast an app is winning new merchants.
Basic
- · 1 Free Offer -Free Gift, Buy More & Save
- · 1-Click Upsells and Cross-Sells
- · AI Translation to Any Language
- · Add-Ons (Shipping Protection, Gift Wrap)
- · Discount in Cart and Subscription Upsell
- · Free Shipping Progress Bar
AOV Boost
- · Everything in Free+
- · Priority Support (Live chat, Call, Wapp)
- · Up to 7 Cart Offers (Schedule Anytime)
Free
Pro
Coverage counts what each App Store listing names. Every feature, checked off app by app, is in Shoplist.
See every featureTurn every cart into a bigger order automatically. 1-time setup. Flex Upsell Cart helps you boost sales by showing smart upsells, cross-sells, and special offers directly inside the cart, without disrupting checkout. Easy to set up, works with any Shopify store. ✅ One-Click Upsells & Cross-Sells: Recommend extra products while customers review their cart.
A free shipping bar tells a shopper they are $23 away, then leaves them to work out what costs $23. Cart Filler does that part: it offers two or three products that close the gap, and adds them in one tap. What matters is when it says nothing. If the gap is $3 and your cheapest item is $40, suggesting it means asking someone to spend $40 to save shipping.
- Easily Setup Gifts for bigger purchases in form of a product or a discount
- Show targeted upsell and cross-sells based on cart content
- Show special one-time offers in cart only
- Only suggests products that actually close the gap - nothing outside that range
- Skips items already in the cart and checks every variant, not just the first
- No access scopes, and your storefront never contacts our servers
All the numbers
Every figure, side by side
A green dot marks the app ahead on a measured figure. Estimates, gaps and apps that leave no storefront trace never take the lead.
Adoption
| Measure |  Flex Upsell Cart Auto Discount |  sK Cart Filler |
|---|---|---|
| Detected stores | 52 | Not published |
| Net store change, 28 days | +2 | 0 |
| Stores added, 28 days | 4 | Not enough data |
| Big-brand share | Not enough data | Not enough data |
| Top store categories | Apparel & Accessories, Health & Beauty, Home & Garden | Not published |
| Top store countries | United States, Australia, Canada | Not published |
Reviews
| Measure | Flex Upsell Cart Auto Discount | sK Cart Filler |
|---|---|---|
| App Store rating | 5.0 ★ | Not published |
| App Store reviews | 18 | Not published |
| New reviews, 28 days | 1 | Not enough data |
| Reviewers a year or more in | Not enough data | Not enough data |
Pricing
| Measure | Flex Upsell Cart Auto Discount | sK Cart Filler |
|---|---|---|
| Free plan | Yes | Yes |
| Lowest paid monthly plan | $19/month | $6.99/month(ahead) |
| Longest free trial | 14 days | 7 days |
| Plans listed | 2 | 2 |
Listing
| Measure | Flex Upsell Cart Auto Discount | sK Cart Filler |
|---|---|---|
| Shopify category rank | #67 | #1106 |
| Shopify App Charts | Not on this week’s charts | Not on this week’s charts |
| Built for Shopify | Yes | No |
| Launched | Jun 3, 2021 | Sep 23, 2026 |
| Languages | 1 | 1 |
| Developer | Flex Upsell | Sait Katmerlikaya |
FAQ
Flex Upsell Cart Auto Discount and sK Cart Filler: common questions
- Is Flex Upsell Cart Auto Discount or sK Cart Filler cheaper?
- Both list a free plan. Paid plans start at $19/month for Flex Upsell Cart Auto Discount and $6.99/month for sK Cart Filler. Shoplist compares base prices only between monthly plans in the same currency; usage charges and annual plans vary, so check each plan’s limits.
- What features does each app list that the other doesn’t?
- sK Cart Filler lists 7 the others don’t mention, such as Cart upsell, Free shipping, Gift wrap, One-click add-ons. A feature missing from a listing may still be supported; this compares what each App Store listing says.
- Where does this comparison’s data come from?
- Shoplist crawls Shopify storefronts to detect which apps each store runs, and reads each app’s Shopify App Store listing for reviews, pricing, features and integrations. Store counts are as of Nov 9, 2026 for Flex Upsell Cart Auto Discount, Oct 13, 2026 for sK Cart Filler; estimated figures are labeled.
How Shoplist compares apps
Store counts come from Shoplist’s crawl of Shopify storefronts, which detects the apps each store runs; they are as of Nov 9, 2026 for Flex Upsell Cart Auto Discount, Oct 13, 2026 for sK Cart Filler. Reviews, ratings, plans, features and integrations come from each app’s Shopify App Store listing. 28-day figures are labeled when estimated, and a figure that is missing or estimated never decides who leads. Read the methodology.