FlatInvoice ‑ PDF Invoice vs Invoice Calculator
Two Shopify apps, side by side: detected stores, momentum, reviews, plans, listed features and who runs each. Store counts as of Oct 13, 2026 for FlatInvoice, Jun 4, 2026 for Invoice Calculator.
The short answer
- Only FlatInvoice lists a free plan.
- FlatInvoice lists 3 features Invoice Calculator’s listing doesn’t mention, including Branding, Color and font, Packing slips.
Head to head
Starter
- · 25 invoices a month, every feature
Flat Plan
Coverage counts what each App Store listing names. Every feature, checked off app by app, is in Shoplist.
See every featureInvoices email themselves the moment an order is placed — every order, every document, nothing to configure. A guided setup adds a Download-invoice button right inside Shopify's own order emails — copy, paste, done. Unlimited invoices, packing slips, receipts, and credit notes, each carrying your logo, with your brand color picked from it in one click. Tax-ready with a VAT/GST tax ID line and sequential numbering.
Suppliers fulfilling orders for your store typically need to invoice you for the unit value of goods after each billing period. This app lets your supplier connect with read-only order access, pull a date range, match each line item to their quotation sheet, and write a fully formatted invoice to a Google Sheet you control.
- One-click PDF invoices and packing slips from any order
- A4 and US Letter formats with automatic page handling
- Your branding: business details, accent color, custom footer
- Paid, pending, and refunded status badges pulled from the order
- Your supplier pulls order data for any date range, including pre-60-day orders
- Read-only access — your supplier can never edit, refund, or modify orders
- Output goes to a Google Sheet your supplier configures and you can review
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 |  FlatInvoice |  Invoice Calculator |
|---|---|---|
| Detected stores | Not published | Not published |
| Net store change, 28 days | 0 | 0 |
| Stores added, 28 days | Not enough data | Not enough data |
| Big-brand share | Not enough data | Not enough data |
| Top store categories | Not published | Not published |
| Top store countries | Not published | Not published |
Reviews
| Measure | FlatInvoice | Invoice Calculator |
|---|---|---|
| App Store rating | Not published | Not published |
| App Store reviews | Not published | Not published |
| New reviews, 28 days | Not enough data | Not enough data |
| Reviewers a year or more in | Not enough data | Not enough data |
Pricing
| Measure | FlatInvoice | Invoice Calculator |
|---|---|---|
| Free plan | Yes | Not listed |
| Lowest paid monthly plan | $5/month | No monthly plan listed |
| Longest free trial | 7 days | Not listed |
| Plans listed | 2 | Not published |
Listing
| Measure | FlatInvoice | Invoice Calculator |
|---|---|---|
| Shopify category rank | #380 | #132(ahead) |
| Shopify App Charts | Not on this week’s charts | Not on this week’s charts |
| Built for Shopify | No | No |
| Launched | Jul 6, 2026 | Jun 4, 2026 |
| Languages | 1 | 1 |
| Developer | Stelar Digital LLC | Invoice Calculator |
FAQ
FlatInvoice and Invoice Calculator: common questions
- Is FlatInvoice or Invoice Calculator cheaper?
- Only FlatInvoice lists a free plan. 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?
- FlatInvoice lists 3 the others don’t mention, such as Branding, Color and font, Packing slips. 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 Oct 13, 2026 for FlatInvoice, Jun 4, 2026 for Invoice Calculator; 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 Oct 13, 2026 for FlatInvoice, Jun 4, 2026 for Invoice Calculator. 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.