Custom Shopify App Development
We build private Shopify apps for one store: live freight rates in checkout, 3D configurators that create real variants, hand-offs to factories and back-office systems. It is the same team that ships four public apps on the Shopify App Store.
Where projects go wrong
An App Store app is built for thousands of stores, so it stops where your process gets specific. Freight that depends on a liftgate question, a product that only exists after the customer designs it, an order that has to reach a factory in a set format. That is usually where three apps and a spreadsheet start, and where one small custom app pays for itself.
01 / Blue Ridge
A custom carrier service app. Checkout calls it through Shopify's HMAC-signed CarrierService request, it packs the cart, asks EasyPost for parcel rates and Echo for LTL freight, and returns real prices. A cart block collects the freight answers (residential, liftgate, appointment) first. It runs on Fly.io next to our Smart Checkout Widgets, which hide and rename the shipping options.
02 / Hably
In build for Hably, a UK media wall brand on Shopify's Grow plan. The imos iX NET configurator sends each design to our service, which prices it from manufacturing cost on the server and only creates a variant when the customer adds it to the basket. The cost never reaches the browser. A paid-order webhook flags the build for the factory, and a nightly job deletes variants nobody bought.
03 / Our own apps
TB Bundles runs on Shopify Functions for discounts and cart transforms. Smart Checkout Widgets adds checkout blocks and shipping and payment rules. Cart Rocket builds checkout-ready cart links. Agentmatica connects a sales and support agent to the catalog, cart and orders. What we learn passing App Store review goes into every client build.
04 / Integrations
Webhooks, scheduled jobs and file hand-offs between Shopify and whatever runs the business behind it: order files for a factory, stock from a warehouse, prices from a cost sheet. We keep Shopify as the source of truth where we can, so there is less to keep in sync and less to break.
Proof you can install
Every public app we run has been through Shopify's review, billing rules and API version upgrades. Custom builds get the same habits: scoped permissions, signed requests, webhooks that verify their HMAC, and a test store before anything touches the live checkout.
Relevant work
TB Bundles, Smart Checkout Widgets, Cart Rocket and Agentmatica, all live on the Shopify App Store.
See our apps →What is included
Scoping call and a written spec listing the Shopify APIs, scopes and plan limits that apply
A custom app on Shopify's current app tooling, installed only on your store
Checkout UI extensions, theme app extensions, carrier service or Shopify Functions (Plus), as the job needs
Webhooks, scheduled jobs and links to your ERP, 3PL, factory or pricing source
Hosting on Fly.io with health checks, logs, and secrets kept out of the code
Handover notes, a development store for testing, and ongoing support if you want it
How the engagement moves
We map the process the app replaces, check what your Shopify plan allows, and write a spec with a fixed quote. Sometimes the answer is an existing app plus a small fix, and we say so.
The app is built and tested on a development store with your real products and edge cases, so the first time it meets your live checkout it has already handled the awkward orders.
We install it on the live store, watch the first orders and logs, and hand over notes on how it works, where it runs and what to do if a request fails.
Specialist Shopify services
Our checkout app: shipping and payment rules on every plan, checkout blocks and gifts on Plus.
View service →Our sales and support agent, installed from the Shopify App Store.
View service →Our cart link app: products, discounts and checkout in one shareable link.
View service →Themes, features, integrations and ongoing development for growing stores.
View service →A custom app is installed on your store only. It skips App Store review and can be shaped around one process, such as your freight rules or your factory's order format. A public app is listed on the Shopify App Store, serves many stores, has to pass Shopify's review and bills through Shopify. We build both, so we can tell you early which one your problem needs.
Only for some parts. Shopify lets custom apps that contain Shopify Functions run on Plus stores only, and checkout UI extensions on the information, shipping and payment steps also need Plus. Webhooks, the Admin API, theme app extensions, app proxies and Thank you and Order status page extensions work on every plan. Carrier-calculated shipping needs the Advanced or Plus plan, or the add-on Shopify offers on other plans.
Custom features and apps start at $3,500. A single-purpose app such as a rate calculator or a webhook sync sits near that end. Configurators, ERP links and anything that writes to orders cost more, because they need more testing. You get a written spec with a fixed quote before work starts.
We host our Shopify apps on Fly.io. A small app usually fits on one shared-CPU machine, which Fly.io lists at $3.69 a month for 512 MB and $6.70 a month for 1 GB, with storage volumes extra. We agree who holds the hosting account and the code in the proposal.
Usually, yes. We start with a short review of the code, the scopes it asks for and where it runs, then tell you what we would keep, fix or rebuild. If the app touches checkout or orders, we test changes on a development store before anything reaches the live one.
Install first if an App Store app covers at least most of the job and the gap is cosmetic. Build when the gap is the job itself: a price that depends on a calculation only you can do, an integration nobody sells, or three apps and a spreadsheet doing what one small service could.
Bring the problem: a leaking checkout, a feature your last developer said was impossible, a store that needs rebuilding. You leave with a straight answer and, if it fits, a fixed-price proposal within 48 hours.
Book a free 15-minute call© 2026 Thought Bulb Studio
No sales call. No deck. Just a direct conversation about your store, what it's costing you, and whether we're the right fit to solve it.
A straight answer on the call, not a follow-up email
Fixed-price, scoped proposal in 48 hours
No retainer, no commitment — just an honest conversation
