Full-stack developer · Systems builder · Project lead

Karl-Erik Wångstedt

I build complete digital business systems – from the first data model to a deployed, secure and maintained product.

Hire me →See my cases Download CV

30+

years in the field

10+

complete systems 2024–26

2,900+

commits in the last two years

languages

Karl-Erik Wångstedt porträtt — Granberg,
Bollnäs

About the legend

The man behind the systems

After graduating as a graphic designer I freelanced while teaching in the same field. Over time I drifted into digital production, which grew into larger and heavier projects – and eventually into running my own companies full-time, focused on digital production.

In recent years my focus has been on complete business systems – backend, frontend, payments, identity and operations in one solution. I work with both national and international clients and happily take end-to-end responsibility: architecture, development, design and project management in one person.

For several years I wrote for the trade magazines CAP&Design and Macworld, and was occasionally hired to speak at large conferences. More recently my passion for languages has taken me to the podium at international language conferences in Berlin, Reykjavík and Bratislava – giving me a broad international network.

For the past 15 years I've lived at Granberg outside Bollnäs together with my dog, and I'm active in several local associations.

Selected work

Five systems I've built in recent years

Complete products and internal systems – not just websites. All planned, built, released and maintained under my lead, with me deep in the data model, API contracts, interface and code.

2024– · own product

The Tekapo platform

Identity, licences and payments in one platform

OAuth 2.0 / OIDCJWT/JWKSNode.js / TypeScriptAngularStripe

Problem

Several products needed the same foundation: secure sign-in, user and permission management, licences and payments – without reinventing the wheel for every new app.

Solution

I built an OIDC/OAuth-based identity platform that manages users, groups, clients, scopes, licences, products and payments. The services are tied together with JWT/JWKS, role control and clear API contracts – with server-side webhook signing, trace IDs in error responses, retry logic and environment-based configuration.

Result

A shared infrastructure that several products build on – with secure authentication, robust operations and a foundation that makes every new app faster to start.

2024– · product

Barkassan

Point-of-sale with Swish, Stripe and a physical till client

Angular / IonicElectronStripeSwishMultitenant

Problem

An organisation needed a complete point-of-sale system tying together digital payment, a physical till and administration – with balances, debts and reconciliation that actually add up.

Solution

I built a multitenant POS with company/group isolation: customer app, admin, backend and an Electron till for desktop and Raspberry Pi (arm64). Swish and Stripe flows for top-ups and payment, device pairing with app passwords, plus balances, debt reminders, refunds and transaction reconciliation.

Result

A deployed system where the payment experience, till environment and finances hang together – with mobile-friendly payment flows, fallback and balance updates straight after Swish.

2024– · product

Makwi Slakt

Production flows for weighing, labels and invoicing data

Angular / IonicElectronZPL labelsSequelizeRaspberry Pi

Problem

A niche abattoir needed digital support for the whole flow: slaughter bookings, weighing, labels and invoicing data – close to physical production.

Solution

I built an admin web app, a weighing app in Angular/Ionic and an Electron app for desktop distribution. The system handles suppliers, price lists, tariffs, animal types, weighing sessions and invoicing flows, with ZPL rendering of label templates and Swedish details like decimal format and millimetre precision.

Result

A business-critical flow support that understands the domain and solves technical details all the way out to the label printer – with a hardened Electron app and safe secrets handling.

2024– · product

Makwi Medlem

Association system with bookkeeping, membership and billing

Angular SSRNode.js / ExpressBAS K1 bookkeepingStripeOIDC

Problem

Non-profit associations and joint property units needed a system where membership, bookkeeping, licences and billing connect – without administrative rules getting lost along the way.

Solution

I built a web app with BAS K1 bookkeeping, a member register with roles and family links, import flows and organisation management. A joint-property module handles properties, invoices and documents, and federation licences are billed usage-based on active members with invoice batches and proportional billing.

Result

Administrative rules translated into clear, usable digital flows – with payment status, PWA launch and responsive lists that work even on small screens.

2024– · client product

Ingeborgs Fastigheter

Property management from public web to internal case handling

AngularReact / ViteSEO / JSON-LDK3 componentsOIDC

Problem

A property company needed everything in one place: a public site for vacant apartments, internal management and an easy way for tenants to report faults.

Solution

I built the API, admin and public web: properties, units, listings, interest and fault reports, cases with comments, attachments, status flows and QR links for quick fault reporting. A tenant portal with rent notices and newsletters, K3 components with depreciation and maintenance, plus SEO improvements for vacant apartments in Bollnäs.

Result

A complete property system where business logic, user flows, SEO and case handling meet – with an admin PWA that is fast and accessible on mobile too.

Smaller projects & assignments

Beyond the larger systems I build web apps, marketing sites and event tools – fast product delivery where the tech level is matched to the brief.

Wångs Golden Jubilee – gala siteNordliga kronan GalaSeating-plan generatorRehabWorksWarpen WebSvea Heraldik v2Dräneringstjänstjakobljungkvist.seFormelmaskinen

Earlier, selected

3-year project

Handikappförbunden

Usability testing tool

Measured usability for 600+ test participants with various disabilities – with secure handling of extremely sensitive personal data.

6+ years

Coca-Cola (UK & Ireland)

Sales tool for field reps

Gathered sales statistics, sales position and competitor data into concrete, data-driven sales strategies.

4 years

Fastighetssnabben

Business-critical systems

Queue system with credit screening and scoring, plus an intranet – with GDPR routines and access control.

Hardware-oriented development

Systems that meet the physical world

Much of what I build doesn't just live in a browser – it runs on real terminals, kiosks and tills out in production. Touchscreens at the cutting table, point-of-sale terminals in the bar, scales and label printers that have to work flawlessly, every day, in a tough environment. I take responsibility for the whole chain: the software, the device it runs on and the peripherals it drives.

Makwi Slakt

Weighing & cutting kiosk

Touchscreen kiosks for weighing and cutting, built to survive a production environment. The operator weighs, registers and prints labels right at the bench – no keyboard or mouse.

Touchscreen kioskRaspberry PiIndustrial scaleZPL label printer

Barkassan

Physical POS terminal

A complete point-of-sale terminal running as a hardened Electron app on desktop and Raspberry Pi. Devices pair securely with app passwords and connect to receipt printers – payment, balance and receipt on the spot.

Electron tillRaspberry Pi (arm64)Receipt printerDevice pairing

Peripherals & operations

Printers, scanners & remote ops

Label and receipt printers, barcode scanners and devices in kiosk mode – deployed, monitored and updated remotely so the business keeps running without hands-on tech.

ZPL labelsBarcode scannerKiosk modeRemote updates

Tech & approach

The whole chain, from data model to operations

I happily take over the whole chain: requirements, architecture, implementation, debugging, release, documentation and ongoing development. AI-assisted development is used as an amplifier – but with my own review, testing, security fixes and full responsibility for the result.

Frontend

AngularIonicReactViteTanStackTailwindPWA

Backend

Node.jsTypeScriptExpressSequelizeRESTOpenAPI/Swagger

Database & ops

MySQL/MariaDBDockerNginxGitHub Actions

Identity & payments

OAuth 2.0OIDCJWT/JWKSStripeSwish

App platforms

CapacitorElectroniOS/iPadLinux/Raspberry Pi

Quality

API contractsMigrationsRelease flowsSecurityAccessibilitySEO

Timeline

Education & work

Download CV

1993–1996

Media programme, print production

1996–1997

Military service

1997–2009

Teacher of graphic design, digital design & film

Upper-secondary & post-secondary (KY)

2004–

Owner

Wångstedt nova AB

2011–2013

CEO

HM Design för alla AB

2019–2024

Software developer

Navigraph KB

2024–

Full-stack developer · business systems

Wångstedt nova & own products

2025–

Co-owner

Makwi AB

Strengths

What I'm genuinely good at

End-to-end ownership of the product

Backend, frontend, database, authentication, payment, deploy and support in one person – from the first data model to a deployed system.

Domain understanding

Invoicing, licences, members, properties, point-of-sale, slaughter bookings and weighing. I understand the rules, the exceptions and everyday use.

Identity, payments & security

Own OAuth/OIDC systems, JWT/JWKS, Stripe and Swish, signed webhooks, role control and robust error handling.

Productisation

Versioned products with releases, CI/CD, Docker and OpenAPI contracts – not prototypes, but systems maintained over time.

Pragmatic frontend

Angular/Ionic, React/TanStack, PWAs, responsive tables, accessibility and mobile-friendly payment flows.

Hardware-oriented development

Kiosks, touchscreen terminals and tills on Raspberry Pi, with scales, label and receipt printers – software that runs and is remotely managed out in production.

AI-assisted development, in control

Modern, fast iteration with Claude, Cursor and Copilot – but with my own review, security fixes and responsibility for the result.

Writer & speaker

Words in print, words on stage

For several years I wrote regularly for the trade magazines CAP&Design and Macworld. They also hired me to speak at large conferences. My love of languages has taken me to the podium at international language conferences in Berlin, Reykjavík and Bratislava.

CAP&DesignContributing writer

MacworldContributing writer

Conference speakerBerlin · Reykjavík · Bratislava

Languages