An app with only 2 ratings climbs to #4 on the Spanish Top Paid chart: a Spanish electrical diagram tool, and the older app behind it that's been around for 6 years

In Oct 29, an app called "Esquemas Eléctricos: Canvas" reached #4 in Spain's App Store productivity Top Paid chart and #74 overall Top Paid. That day it had only 2 ratings worldwide. It sells for 2,99€ and lets electricians draw electrical diagrams on their phones. It looks like a new app that popped up out of nowhere, but it's really a Spanish developer rewriting an app they've run for 6 years, using user reviews as the guide. Here's who it's for, why a handful of ratings was enough to chart, where the money comes from, and whether you could build something similar for another trade or language.

A three-star review from 2024 years ago

In 2024 Aug 2, a Spanish user gave an app called "Unifilar - Esquemas eléctricos" three stars:

"Still needs improvement, but it's perfect for drawing quickly. It would be great if you could export directly to dwg or dxf. Another useful feature would be a visible title block on the drawing, with the author, location, date..."

Unifilar was released by Angel Martinez in December 2020, and does just one thing: single-line diagrams (esquema unifilar), the simple sketches electricians use for distribution boards and circuits. Reviews from the same period asked for much the same: a Mexican user said "I'd buy it right away if it ran on my MacBook" (2023-10), a UK user listed five points including "choose component and wire colors" and "make a Mac version" (2025-09), and several Italian users complained that residential circuit symbols were insufficient (2023).

Two years later, almost all of these requests show up on the new app's store page: 400+ IEC / ANSI symbols, multi-line diagrams and control circuits alongside single-line, colorable wires, an iPad version that runs on Macs from M1 onward, a web version at electricalcanvas.com, and separately sold DXF export at 0,49€ one-time. The new app was released in Aug 12 and updated to 1.6.0 in Nov 4.

What it sells

In one sentence: an electrical schematic editor for phones and tablets. Drag components from a symbol library onto a canvas, connect wires, export PDF or images, and pay 0,49€ once to convert to DXF for CAD.

Pricing has three tiers (Spanish App Store, 11-06):

The "only 2 drawings" limit is very direct: an electrician finishes one today, takes another job next week, and the third costs 6,49€. The old app cost 1,99€ to download and Pro 4,49€ (a French user said that price in a review 2023 years ago). The new app costs more at every tier and adds a pay-per-use hook.

Who buys? Low-voltage electrical installations in Spain require a set of documents, including a single-line diagram. Catalonia's government list of required documents for owners gives the single-line diagram its own form (ELEC-2). So every renovation or shop fit-out an electrician takes on needs one of these diagrams. They used to be drawn on desktop CAD or by hand. Now they can be drawn on site on a phone and exported as a PDF.

Why 2 ratings is enough to chart

The answer: efficiency Top Paid charts in countries like Spain and Estonia have such low thresholds that a few purchases a day can reach the top ten.

The new app looks the same on every country chart: it spikes, then drops every day (productivity Top Paid category chart):

Throughout this period its global ratings stayed at 0 to 2, with no new reviews. The same-named new app on Google Play has only 100 downloads (11-02). How much the new app sells itself is not visible from outside; at these small-chart thresholds, that's likely single digits to a few dozen purchases a day, and monthly revenue may be only a few hundred euros (estimate).

The real engine is the older app. Unifilar has 270 iOS ratings in Spain (4.6 stars), 133 in the US store, 157 in Italy and 126 in Germany, and has appeared on productivity Top Paid charts in 71 countries. In Nov 4 it was #1 in Spain's productivity Top Paid chart and #36 overall Top Paid. Its Android version is free with ads and has 500k+ downloads and 5,410 reviews, rated 4.2 stars on Google Play (11-06). The new app's title takes the two most-searched Spanish terms, "esquemas eléctricos" and "unifilar". The developer's profile page lists the new and old apps side by side, and the website groups the web, Android and iOS versions together. Users most likely arrive from the old app and search. Whether the old app links to the new one or the new one runs Apple Search Ads was not found.

Other channels are nearly nonexistent: the developer's YouTube channel has 444 subscribers, and the new app's launch video premiered in Oct 16 and had 6 views by Nov 154. Searching TikTok for "electrical diagram app" or "single-line diagram app" in Spanish doesn't surface it, nobody has mentioned it on X in 90 days, and no media has written about it.

Who it's competing with

On the App Store, the slot for "Spanish + phone + drag-and-drop professional electrical symbols" is basically held by just this developer's two apps.

• English-major tool: Circuit Planner (iPad, $7.99,1,070 symbols, automatic wiring, cross-references), more like CAD. It only supports English and German, and its US-store rating count is too low to display.
• Desktop software: ProfiCAD, QElectroTech, AutoCAD Electrical, EPLAN. Commonly used by European electricians and engineers, but they don't run on phones, and are expensive and heavy.
• General drawing tools: draw.io, Canva's circuit templates, Scheme-it. Free, but symbols don't follow IEC standards and there's no DXF export.
• Free tools from big brands: Schneider's EcoSet Config picks devices and auto-generates switchboard and single-line diagrams, but only with Schneider's own components. A TikTok introduction video has 123k views (10-16).
• The new AI route, the real threat: around October 2026, several Android tools appeared on Spanish TikTok promising "take a photo of the distribution board and AI generates the single-line diagram" or "single-line diagram plus simulation plus AI". Their views ranged from hundreds to thousands, still small. If one of them gets good enough, "manually dragging symbols" itself becomes unnecessary.

What users are complaining about

The old app's bad reviews cluster around three issues, and the new app will get the same criticism if it doesn't fix them:

• Paying twice: "I paid for the download, then to save projects I had to pay for PRO again... tapping restore purchases does nothing" (Brazil, 2026-02); "I paid 4.49 euros for Pro and nothing changed except the charge" (France, 2023-10). The new app makes "only 2 drawings" even tighter, so these complaints will likely keep coming.
• Lost images: "Wasted money, keeps crashing, saved images won't open" (Spain, 2025-11); "Saved it, but reopening it shows nothing" (UK, 2023-09).
• Missing symbols: Italian users say there are no two-way or changeover switches for residential circuits (2023); a Spanish user says common symbols like crossing wires are missing (2025-11).

Almost all the good reviews mention the same two things: it's simple, and the developer replies fast. "The update to Pro had a problem, and they fixed it right away" "The developer is in Spain" (Spain, 2024-03). For a tool run by one person, customer service is part of the moat.

If it were you

Verdict: C. You can learn a very clean playbook from it, but copying it isn't worth much. It charted because of 6 years of accumulated older apps, 500k Android users, and Spanish search terms that new entrants can't get; the money ceiling is also low (a new app might make a few hundred euros a month); and AI photo-to-diagram tools are sidestepping manual drawing altogether.

Who it's for: people who already work in a trade (electricians, plumbers, gas, solar PV, HVAC), or who have friends or relatives in those trades who can give you daily feedback; people who can build for iOS / Android, can accept a side income of a few hundred to a few thousand euros a month, and are willing to grind on it for years.

Who it's not for: people who want to jump straight into Spanish-language electrical drawing (this developer already holds the search terms and older users, and keeps updating); people who want full-time income or fast payback; people who don't know the trade and can't draw compliant diagrams (a common complaint in the older app's bad reviews is "missing symbols").

How to do it: switch to a different trade or a different language, and copy its structure. Find a blue-collar trade that has mandatory paperwork that must include a diagram, and build a drag-and-drop diagram tool for phones in one language; draw the symbols fully to local standards; charge a download fee, add "save more" and "export CAD format per use." The Android version can be free with ads to build reach, with iOS making the money. Start with a narrow version (like Unifilar doing only single-line diagrams), collect reviews, and build the second generation from them. Avoid designs that make people "pay and then pay again"; spell out the one-time purchase and Pro clearly.

How to get users: store search. Use the two words practitioners actually search for in the title and subtitle (look at it: "Esquemas Eléctricos" plus "Diagrama unifilar & multifilar"), translate the store listing into 7 languages, and use local-language titles in each country. Then rotate through the productivity paid mini-charts in each country, using releases and new-country launches to pop up. These charts can get you into the top ten with a few sales a day, and a chart spot brings a bit of organic traffic. Then show up in local electrician and plumber Facebook groups and on YouTube tutorial sections.

When to go before it's too late: there's no deadline, this is a slow business. But if the trade you plan to target already has "photo-to-AI diagram" tools with hundreds of thousands of TikTok views, don't build manual drawing; go straight for the AI route.

Signs you've read this wrong: (1) Canvas was still rated in single digits before spring 2027 and kept dropping off the Spanish charts, which would show that even someone with an existing user base can't push a second generation, meaning this business is smaller than it looks; (2) one of the Spanish "photo to single-line diagram" tools reaches 100k views on video and tens of thousands of Android downloads, which would mean the manual-drawing path is narrowing; (3) conversely, if the similar apps you find in another trade or language haven't been updated in years and reviews are full of complaints, that's a real gap, and you can raise the grade to B.

Data and sources

• Store page and pricing: App Store Spain id6797312801 (11-06), iTunes lookup (es / us / mx, 11-06); older app id1534899128 lookup (es / us, 11-06).
• Charts: App Store productivity paid category charts and the overall paid chart across countries, daily records from 2026-10-28 to 11-06.
• Reviews: public App Store reviews for Unifilar and the same developer's "Esquemas hidráulicos" (2023-06 to 2026-03), original text in Spanish / English / Portuguese / French / Italian, Chinese is translation.
• Google Play: com.xlingenieria.unifilar (500k+ downloads, 5.41K reviews, 4.2 rating, 11-06); com.electricalcanvas.app (100+ downloads, 11-02).
• Website electricalcanvas.com/es (11-06); YouTube kPbLICdn6I4 (154 views), ElectricalSoft channel.
• Single-line diagrams are a required document: Catalonia government's "documents owners of low-voltage installations must provide" page (ELEC-2 single-line diagram); Spanish Ministry of Industry GUÍA-BT-04.
• Competitors: Circuit Planner store page; public videos from accounts such as @automatismosmundo on TikTok (2026-10).
• Revenue is estimated; there are no public revenue figures.