ConvertBoost vs Fast Bundle: Flat-Rate Architecture & Limits Review
Compare ConvertBoost vs Fast Bundle for Shopify tiered quantity breaks: flat-rate pricing, Theme App Extension architecture, and checkout discount limits.
Quick Verdict (TL;DR) ConvertBoost offers Shopify Theme App Extension blocks for tiered quantity breaks and comparison cards at a flat $9.99/month with 0% GMV cut, while Fast Bundle is a separate bundle app with its own pricing and feature set. Both must navigate Shopify's native checkout discount rules; ConvertBoost syncs selected quantities with the native product form, but automatic discount stacking requires checkout verification.
Merchants using bundle apps often face unpredictable costs from GMV-based fees and integration issues where quantity selectors fail to update the native Shopify product form, leading to cart errors. Additionally, automatic discounts may not combine as expected in checkout, causing customer confusion and lost sales. Without transparent pricing and reliable form synchronization, merchants risk revenue leakage and poor user experience.
What to check first
Check how the bundle block integrates with Shopify Online Store 2.0 Theme App Extensions, whether quantity selection updates the native product form variant/quantity inputs cleanly, and how automatic discounts or price tiers behave in Shopify Checkout. Compare Fast Bundle workflows against ConvertBoost using verifiable public platform rules and transparent pricing boundaries.
Side-by-side comparison
| Aspect | Status Quo / Legacy Bundle Apps (e.g., Fast Bundle) | ConvertBoost |
|---|---|---|
| Pricing model | Often includes GMV-based fees or tiered subscriptions; total cost scales with sales | Flat $9.99/month subscription; 0% GMV revenue cut |
| Architecture | May rely on external runtimes or full app embeds; integration depth varies | Built as Shopify Theme App Extension blocks using native Liquid, CSS, and lightweight JavaScript |
| Native form sync | Quantity selection may not update native product form variant/quantity inputs cleanly, risking cart errors | Synchronizes selected bundle quantities with the native Shopify product form |
| Discount behavior | Automatic discounts may not stack; checkout rules apply per Shopify's combining discounts policy | Tiered pricing is applied via the bundle block; automatic discount stacking requires checkout verification per Shopify rules |
| Platform boundaries | Features depend on app's own implementation; Shopify App Store approval status varies | Provides blocks for tiered bundle quantity breaks and side-by-side comparison cards; no claim of Shopify App Store approval |
How to work through it
- Install ConvertBoost and enable the Theme App Extension in your Shopify theme editor (Online Store 2.0 required).
- Add the Tiered Bundle Quantity Breaks block to your product template and configure quantity tiers and discount rules.
- Verify that quantity selection updates the native product form variant and quantity inputs by testing on a preview theme.
- Set up any automatic discounts in Shopify admin and test checkout to confirm they combine correctly with bundle pricing (Shopify's discount combination rules apply).
- Optionally add the Side-by-Side Comparison Cards block to product pages to highlight bundle value.
- Monitor performance and adjust tiers based on customer behavior; use ConvertBoost's flat pricing to forecast costs without GMV fluctuations.
Where the product fits
ConvertBoost is designed for Shopify merchants using Online Store 2.0 themes who want transparent, flat-rate pricing for tiered quantity breaks and comparison cards. It integrates via Theme App Extensions and syncs with the native product form, but does not provide automatic discount stacking beyond what Shopify checkout supports. It is not a full bundle app for complex bundle types (e.g., mix-and-match or subscription bundles) and does not claim Shopify App Store approval. Merchants should verify theme compatibility and checkout discount behavior.
Next step
Start with ConvertBoost's flat $9.99/month plan and test tiered bundles on your Shopify store. Visit https://convertboost.getsearivo.com to install and review documentation.
Frequently asked questions
How does ConvertBoost's pricing compare to Fast Bundle?
ConvertBoost charges a flat $9.99/month with 0% GMV revenue cut, while Fast Bundle's pricing may include GMV-based fees or tiered subscriptions. Check Fast Bundle's current pricing for exact costs.
Does ConvertBoost support automatic discount stacking in Shopify checkout?
ConvertBoost applies tiered pricing via the bundle block, but automatic discount stacking depends on Shopify's checkout rules. You must verify discount combinations in checkout; ConvertBoost does not guarantee stacking.
Is ConvertBoost a replacement for Fast Bundle?
ConvertBoost focuses on tiered quantity breaks and comparison cards via Theme App Extensions, while Fast Bundle offers a broader bundle app feature set. Evaluate based on your need for flat-rate pricing and native form sync.