sisl.pl
sisl.pl — est. 2021
sisl.pl — est. 2021

SISL.PL — boutique web studio in Poland: custom websites, online stores and technical SEO

// independent // studio // web //

A team of web application enthusiasts. We build custom websites that work, attract, and earn.

// FOR INTERNATIONAL CLIENTS

Why hire a Polish boutique dev studio for your project?

  • Same time zone as Western Europe. Warsaw is GMT+1/+2 — overlaps every working hour with Berlin, Amsterdam, Paris, London. No 3 AM Slack pings, no async-only workflows.
  • EU-native (GDPR, ePrivacy, DSA). We've built and shipped under the same regulatory framework as your German/French/Dutch business. No "we'll figure it out" stage on cookie consent, data residency, lawful basis.
  • Western-grade engineering at a Polish rate. Senior dev day-rate sits at 35–45% of equivalent Berlin/Amsterdam rates without sacrificing English fluency, code review discipline, or test coverage.
  • Boutique, not body-shop. Every project goes through one senior who owns the full stack — not a 5-person "team" where the lead is on three other projects. You always talk to the person who writes the code.
  • Modern stack, no fragile WordPress glue. FastAPI, Next.js, Astro, Magento for e-commerce, Postgres + Redis, Docker-first deploys. Same toolbox we use for our own products (live: sisl.pl/battlemap) — proven on real production traffic, not just demo decks.

Invoicing in EUR or USD on request. NDA + IP assignment template available. Standard contract: monthly retainer or fixed scope; 50/50 milestone split for projects above EUR 5,000.

50+
delivered projects
5
years of experience
99%
satisfied clients
<24h
response time

What we do
best

Every project starts with understanding your business. The best website is one that works for your success.

01

Websites & web apps

From landing pages to SaaS platforms. React, Next.js, Python — we choose the stack based on needs, not trends.

02

UI/UX Design

Interfaces that are beautiful and intuitive. Every pixel has a purpose — guiding users to action.

03

E-commerce

Online stores that sell. Payments, logistics, management panels — turnkey solutions.

04

SEO & Optimization

Your website can be a masterpiece, but without traffic it’s an empty gallery. Visibility from day one.

05

Automation

Bots, API integrations, dashboards. We automate repetitive tasks.

06

Maintenance & support

We don’t disappear after launch. We monitor, update, and grow.

From idea
to launch

Transparent process, regular communication, zero surprises.

01 //

Discovery

We talk about business, goals, and target audience. We define the scope.

02 //

Design

Wireframes and prototypes. We iterate until it’s just right.

03 //

Build

Clean code, tests, code review. We show progress regularly.

04 //

Launch

Deployment, monitoring, training. Then ongoing care and growth.

Selected
work

Every project is a different story. What they share — clients who come back.

mockql
Aplikacja webowa

mockql

MockQL is a hosted GraphQL mock server that turns any SDL schema into a live endpoint in one click — no backend setup, no resolver boilerplate, no fixtures. An AST-driven engine infers behavior for every type (scalars, objects, lists, enums, unions, interfaces, recursive references) directly from the schema, with deterministic fake data from @faker-js/faker

PgX-Ray - Postgres EXPLAIN Visualiser
Next.js 14 · React 18 · TypeScript (strict) · React Flow · Zustand · Tailwind · i18n (EN/PL)

PgX-Ray - Postgres EXPLAIN Visualiser

A client-side visualiser for Postgres EXPLAIN (ANALYZE, FORMAT JSON) plans — paste the JSON, get an interactive graph with heatmap-coloured hotspots and automatic "Smart Insights" that flag sequential scans, row-estimate drift, Nested Loop explosions and work_mem spills. Runs entirely in the browser — no data leaves the tab. Next.js 14 (static export), React Flow, strict TypeScript, Zustand, Tailwind; EN/PL with locale-aware number formatting; 120 tests across parser, rule engine, XSS surface, determinism and dictionary parity.

Hookzy
Aplikacja webowa

Hookzy

Check if your webhook works

Check your store. Free.

Enter an address and in ~30 seconds see what your Magento 2 exposes publicly: files that should not be reachable, security headers, technical SEO and performance measured on real users (Chrome UX Report). No login, nothing to install in the store — only what every visitor can already see.

Run a free scan

Pricing — on the table.

All prices net (VAT 23%), fixed-price for defined scope. Final quote in 24h after brief. Subscription for small biz, fixed projects for everything else.

// business card site

Business card site

from 1 200 zł

5-10 pages, themed + customised, contact form, basic SEO. Hosting separately.

  • Mobile-responsive design
  • Core Web Vitals optimisation
  • Schema.org markup
1-2 weeks
// landing page

Landing page

from 1 500 zł

Single high-converting page for Google/Meta Ads. A/B-ready, Pixel + GA4 wired.

  • Mobile-first hero + CTA
  • Conversion tracking setup
  • LCP < 2.5s guaranteed
5-10 days
// company site

Mid-market company site

from 5 500 zł

15-30 pages, full custom UX/UI, copywriting support, multilang, integrations.

  • Custom Figma design + WordPress / headless CMS
  • Mailchimp / HubSpot / Calendly hooks
  • PL + EN versions, hreflang, schema.org
3-6 weeks
// woocommerce

WooCommerce store

from 5 500 zł

Up to 1000 SKUs, Polish payment gateways, InPost / Orlen, vouchers, B2B basic.

  • Przelewy24 / PayU / BLIK / Stripe
  • Custom theme or fork of starter
  • Voucher system + email automation
3-8 weeks
// custom web app

Custom web app / SaaS MVP

individual quote

React/Next.js + FastAPI/Node, auth, admin panel, Stripe Billing, Postgres, Docker deploy.

  • Multi-tenancy + role-based access
  • Stripe Subscriptions + invoicing
  • Sentry monitoring + CI/CD pipeline
6-12 weeks
// after delivery
Maintenance from 549 zł/mo
BASIC / PRO / ENTERPRISE — uptime, backups, updates, security
// SEO
SEO retainer from 1 500 zł/mo
// full price guide
Pricing 2026 article

Need something not on the list? Just ask — quote in 24h.

Got an idea?

No matter the stage — a sketch on a napkin or a full specification.

get in touch

Let’s build
together

Every collaboration starts with a conversation. Zero obligations.

new-message.sh

Tell us about
your project

Fill out the form or write directly. We respond within 24 hours — usually faster.

lokalizacja Polska / zdalnie
odpowiedź < 24h
enter ↵