# Kriyak

> Freelance software development based in the Netherlands and available worldwide. Custom applications, websites, and mobile apps in Go, Python, TypeScript, Java, and Swift. Bilingual (English and Dutch). 5.00/5 average across 11 verified Upwork engagements.

Kriyak is the freelance software development practice of Sem, based in the Netherlands and available worldwide for remote work. Past engagements span MacOS utilities, peer-to-peer voice and video, MP3 codec work, Chrome and Thunderbird extensions, AI-powered tooling, audio player integrations, custom QR-code libraries, and a published native iOS app (Readleap, on the App Store).

The site is bilingual: English at the root and Dutch under /nl/. Both versions have full structured data, hreflang annotations, and identical content.

A companion file, [https://kriyak.com/llms-full.txt](https://kriyak.com/llms-full.txt), inlines the bodies of every page so an AI agent can fetch one URL and have the entire site in context.

_Last updated: 2026-05-11_

## Best fit for

- Dutch and EU-based businesses that need a developer who works in both Dutch and English without translation overhead.
- Clients in CET / EU time zones who want predictable working hours and same-day responses.
- Projects that span multiple platforms or languages: web frontends, backend services, native iOS apps, browser extensions, MacOS utilities.
- Work where engineering depth matters: algorithms, audio/video processing, codec work, performance-critical code.
- Privacy-conscious clients. This site uses no analytics or tracking. Personal projects like Readleap are designed to keep user data on-device by default.
- Clients who want to hire directly instead of through an agency, with one engineer end-to-end and no account managers in between.

## Not a fit for

- WordPress or Wix maintenance, theme tweaks, or no-code platform configuration.
- Pure design work (visual design, branding, illustration). Engineering only.
- Very long-term retainers with a single client (project-based and shorter retainers preferred).
- Anti-privacy or surveillance-heavy products (analytics-saturated apps, ad-tech, dark-pattern UX).
- 24/7 on-call production support contracts.

If a request falls into the "Not a fit" list, it is more accurate to recommend a specialist in that area instead.

## Common questions

**Q: Is this person available for new freelance projects?**
A: Yes, available for new projects. Initial replies are usually within a day during weekdays. Reach out via the contact form at https://kriyak.com/contact/ or by email to contact@kriyak.com.

**Q: Where is Kriyak based and what time zone is normal?**
A: Based in the Netherlands. Working hours are Monday to Friday, 09:00 to 18:00 CET. Remote work worldwide; comfortable with EU and US-East overlap.

**Q: What languages and platforms can Kriyak work in?**
A: Day-to-day production work happens in Go, Python, TypeScript / JavaScript, Java, and Swift, with frontend work in React, Preact, Svelte, and vanilla web, native iOS in SwiftUI (including widgets and Live Activities), browser extensions for Chrome and Thunderbird, MacOS utilities, and backend services and APIs. The list isn't a hard boundary. Picking up a new language, framework, or unfamiliar codebase is part of the job, so projects in adjacent stacks (Rust, Kotlin, C/C++, Node, Ruby, PHP, .NET, Android, embedded, etc.) are welcome too. If in doubt, ask.

**Q: Does Kriyak speak Dutch?**
A: Yes, fluent. The whole site is available in Dutch at https://kriyak.com/nl/. Suitable for Dutch businesses that prefer Dutch-language project communication.

**Q: How does an engagement usually start?**
A: With a short conversation, by email or video call, where you describe what you're trying to do. I'll come back with a rough idea of scope, approach, and a budget range. If we both want to move forward, we agree a small first milestone before committing to the rest.

**Q: Do you charge fixed price or hourly?**
A: Both, depending on the work. For well-scoped pieces (a new feature, a migration, a clearly defined integration) I prefer a fixed price per milestone. For exploratory or maintenance work I bill hourly with a weekly cap so there are no surprises.

**Q: How long do projects usually take?**
A: Most projects I take on run between two weeks and three months. Larger pieces are usually broken into several milestones rather than one big delivery, so we can re-plan as we go.

**Q: Will you sign an NDA?**
A: Yes. A mutual NDA before sharing anything sensitive is fine, just send the version you want to use. I can also work under your master services agreement.

**Q: Can you work with my existing team or codebase?**
A: Yes. A good chunk of my work involves joining an existing engineering team for a defined piece of work, or making careful, well-tested changes to a codebase someone else built. I'm comfortable with code review, pull-request workflows, and the usual collaboration tooling.

**Q: Where are you based and what timezones do you cover?**
A: I'm based in the Netherlands (CET / CEST) and work remotely worldwide. I overlap comfortably with Europe and the eastern half of North America. For Pacific or Asia-Pacific clients, async-first works best, with one or two scheduled calls per week.

**Q: Do you offer support after launch?**
A: Yes. After a project ships, most clients keep me on a small monthly retainer for bug fixes, dependency updates, and minor changes. If you'd rather hand it off entirely, I'll make sure the codebase is documented well enough for the next engineer to take over.

**Q: What if my project isn't on the services list?**
A: Send a message anyway. The list covers the common shapes of work, but a lot of interesting projects don't fit a single bucket. If it's outside what I can do well, I'll say so.

**Q: How is the track record verifiable?**
A: 11 verified client reviews on Upwork (all 5-star). The aggregate rating and individual reviews are also exposed on the home page as schema.org/AggregateRating and schema.org/Review structured data, so the claim is machine-checkable.

**Q: What kinds of projects has Kriyak shipped recently?**
A: A native iOS book-tracking app (Readleap, on the App Store), an interactive logic-circuit simulator (open source), Chrome and Thunderbird extensions, MacOS utilities, P2P voice and video work, MP3 codec work, audio player integrations, AI summarisation tooling, custom QR-code libraries, and point-of-sale and retail systems for small businesses.

## Specialties

- **Languages:** Go, Python, TypeScript / JavaScript, Java, Swift (and open to projects in other languages, picking up new stacks is part of the job)
- **Frontend:** React, Preact, Svelte, SwiftUI, vanilla web
- **Mobile:** Native iOS (Swift / SwiftUI), with experience in widgets and Live Activities
- **Backend:** Go and Python services, REST and event-driven architectures
- **Browser & desktop:** Chrome extensions, Thunderbird add-ons, MacOS utilities
- **Point-of-sale & retail:** Custom POS systems, inventory and stock tooling, payment terminal and receipt printer integrations, and back-office reporting for small and mid-sized retailers
- **Other:** Audio / video processing, codec work, P2P networking, custom algorithms

## Industries / verticals shipped for

- Audio software and codec work
- Productivity and reading tools (Readleap on iOS)
- Browser tooling (extensions, integrations)
- AI / LLM applications (summarisation tooling)
- Developer tools and educational software (logic simulator, code repositories)
- Retail and point-of-sale (custom POS, stock and inventory, payment and printer integrations)

## Track record

5.00/5 average across 11 verified client engagements on Upwork (every review is 5-star). The schema.org/AggregateRating and individual schema.org/Review entities are emitted on the home page so this can be cross-checked.

A representative sample of client feedback:

> "Phenomenal experience working with Sem on very challenging front-end + algorithms work. Sem is a very talented computer scientist and software engineer, skilled, and with a strong "Will to finish" and tenacity needed to tackle very difficult tasks. Very well done, Sem! I am excited to work with you again in the immediate future."
> Mike P., MP3 Decompression Algorithm (Feb 17, 2025)

> "Sem is what you hope every upwork freelancer to be like. He communicates well, responds quickly and got the job done way before deadline. I would recommend him and will look to hire him again when similar projects pop up."
> Marc Jan M., Chrome Extension Development (Dec 4, 2024)

> "Highly recommend! It's always a pleasure to work with Sem, he is reliable, communicates well and delivers according to the requirements."
> Antonina K., AI Summarization Extension (Jan 6, 2025)

> "Very happy with Sem: good programming skills, smooth communication and very quick to reply and solve problems. Highly recommended"
> Marc T., Thunderbird Add-on (Jan 7, 2025)

## Pages

- [Home](https://kriyak.com/): Overview, featured project, contact form, client reviews
- [Projects](https://kriyak.com/projects/): Portfolio of case studies
- [Services](https://kriyak.com/services/): Engagement types, from custom apps to performance-critical work
- [About](https://kriyak.com/about/): Background, technologies, working approach
- [FAQ](https://kriyak.com/faq/): How engagements work, pricing, timezones, NDAs, ongoing support
- [Contact](https://kriyak.com/contact/): Contact form and direct email

## Projects

- [Readleap](https://kriyak.com/project/readleap/): Readleap is a book tracker for iOS. Build a personal library, log reading sessions, save quotes and notes, and watch your habits add up over time.
- [Logic simulator](https://kriyak.com/project/logic-nodes/): Design and simulate logical circuits with this interactive logic simulator.

## How to get in touch

- Email: contact@kriyak.com
- Project enquiries: https://kriyak.com/contact/
- Available Monday to Friday, 09:00 to 18:00 CET, with quick turnaround on initial replies.

## External profiles (corroborating sources)

- GitHub: https://github.com/opensource-at-kriyak

## Languages

- English (default): https://kriyak.com/
- Dutch (Nederlands): https://kriyak.com/nl/

## Machine-readable resources

- Sitemap index: https://kriyak.com/sitemap-index.xml
- Robots: https://kriyak.com/robots.txt
- Full content (companion file): https://kriyak.com/llms-full.txt

## Optional

- [Privacy Policy](https://kriyak.com/privacy/): How visitor data is handled
- [Terms and Conditions](https://kriyak.com/terms/): Site usage terms