Full-Stack Developer · Independent

StanislavShtelmakh

Next.js · TypeScript · Python. Production SaaS, self-hosted on Linux. The stack is not a checklist — it is one product surface, refracted from interface to ops.

Product spectrumOne surface from interface to operations.
Next.jsInterface
TypeScriptContract
ReactInteraction
PythonAutomation
FastifyRuntime
StripeCommerce
Docker/LinuxOperations
3Live Products
3-in-1Widget Channels
99/100Lighthouse Perf
1000+Concurrent Licenses
AI Agent Engineering

Sezon Mail — AI Email Agent in Telegram

Live in ProductionSingle-Tenant by Design

Email That
Triages Itself

LLM-judged email triage for a B2B client: model-decided importance with a deterministic safety net, and a feedback loop that changes behavior without a code deploy.

TypeScriptgrammYNext.jsFastAPIGeminiPrismaResend
≈4daysFirst commit
→ production
0Hardcoded
triage rules
2/1Two surfaces
one Prisma schema

Single-tenant by design — one inbox, one owner. Scoped deliberately small instead of building multi-tenant infrastructure nobody asked for yet.

Live Triage
Inbound
Model judgment
Route
Invoice #2214 — payment due Friday
billing@supplier-eu.com
supplier-invoiceHigh0.91Safety net
Pushed to Telegram
Your campaign is now live
noreply@ads.google.com
ads-notificationLow0.94
Filed to feed
Пропозиція співпраці
olha@newpartner.com.ua
partnership-inquiryReview0.34< 0.40 → never filed
Surfaced anyway
Deterministic regex overrides the model — payment, invoice, refund & legal content always surfaces, in EN · UA · RU.

Taught, Not Deployed

Inline feedback and plain-language rules persist to Postgres and change future triage — zero code deploys.

New · High importance

Invoice #2214 — payment due Friday

Important Not this
Preference saved — future triage updated

Write Before Triage

Every inbound path verifies its signature synchronously and persists before any slow work. A model failure can never lose a message.

Svix HMAC verifiedsync
Acknowledged< 9s
Postgres writebefore AI
Gemini triagebackground

Contracts That Can't Drift

The bot ↔ AI-service wire format is mirrored on both sides — it can't change without both languages visibly changing together.

TypeScript
Zod
camelCase
Python
Pydantic
One HTTP contract · two typed mirrors

Split-Host Production

VPS · Docker
grammY bot
FastAPI · Geminiinternal-only network
Postgres
One Prisma schemashared by both surfaces
SSL, opt-in exposureloopback-only stays the fleet default
Vercel
Telegram Mini AppinitData auth
Full inbox feedNext.js · Prisma Client
Second production bot on this fleet — live with zero new domains, certificates, or DNS records.

Architecture Notes

Model-judged triage, the deterministic safety net, and two production failures diagnosed to root cause in the first week.

End-to-End SaaS

Next.js + Fastify SaaS — Multi-Channel Chat Widget

Shipped SaaSEnd-to-End Product

Next.js + Fastify SaaS
Multi-Channel Chat Widget

$39 Lifetime License. Self-hosted WhatsApp, Telegram & Viber widget micro-product with Stripe payments and domain-bound keys.

TypeScriptNext.jsFastifySQLiteStripe
Lifetime Deal

The $39 Micro-SaaS

Most widgets charge $29/mo and inject trackers. PingBoost is self-hosted, domain-bound, and requires a single one-time payment.

Multi-Channel Ready
No Trackers
100% Self-Hosted

SaaS vs Self-Hosted

Metric
OthersPingBoost
Pricing
$29/mo
$39 flat
Channels
Separate widgets
3-in-1
Trackers
Yes
None

System Specs

FrontendNext.js (Static)
BackendFastify + SQLite
PaymentsStripe Webhooks
DeliveryResend API

Zero-Touch Automation Loop

Visitor
Stripe
Email Key

System Infrastructure

ModuleKey Capability
Embeddable WidgetMulti-channel fail-silent payload
License ServerIdempotent Stripe webhooks
Marketing LandingStatic export via Nginx
Visual EditorZero-touch configuration
B2B Automation

Bulk Price Updates in 2 Minutes

ProductionBrowser-Based

Bulk Price Updates
in 2 Minutes

Browser-Based Tool for E-commerce

TypeScriptReact 19Next.js 16SheetJSPapaParse
Zero Upload
10kProducts

Processed locally in < 2s.
Business data never leaves the browser.

Hierarchical Rules

Global: +5%
Category: +10%
Subcategory: +15%

Auto-Detect

Algorithms map columns across formats automatically.

"Ціна"PRICE
"Артикул"SKU
SKU
Category Tree
Raw_Export
Computed_Price
FURN-01
Chairs > Office
1 240,55
1,450.00
FURN-02
Desks > Standing
4500.10
4,950.00
FURN-03
Storage > Cabinets
890,99
1,050.00
FURN-04
Chairs > Gaming
2100
2,500.00
FURN-05
Desks > Basic
1150,40
1,300.00

Zero-Backend Export

Format-preserving export entirely in the browser. 50+ columns kept intact.

SheetJS
PapaParse

Architecture Docs

Deep dive into the core browser-based processing engine logic.

Infrastructure

Linux Homelab Stack

Production · Live 24/7Ubuntu 22.04 LTS

Linux Homelab
Infrastructure Stack

Production-Ready Self-Hosted Infrastructure

DockerTraefikPrometheusGrafanaUbuntu 22.04
stan-homelab
Uptime99.99%
Active Containers7 / 7
Sys Load
Auth
Key-only SSH
Firewall
UFW strict
Brute-force
fail2ban
Backups
Nightly cron
Updates
Watchtower

SaaS List (V3)

Clean badges and modern typography.

Traefik Reverse Proxy

Seamless routing with automatic SSL provisioning. All internal ports stay hidden.

Architecture Docs

Explore the complete infrastructure as code and full setup documentation.

Network Architecture

Real-time visualization of the homelab network topology

Traefik Proxy
Entrypoint & SSL
Grafana & Dashboards
Uptime Kuma
Prometheus TSDB
Watchtower Updater
Research & Development

System Architecture

In DevelopmentWindows Server 2022

Research & Development
System Architecture

Advanced configuration and terminal environment

Active DirectoryGroup PolicyPowerShellDNSWindows Server
dc01.corp.local
AD SyncHealthy
DNS/SMBActive
Sys Load
Role-Based Access
Strict RBAC
NTFS Security
Delegated ACLs
Direct Assignments
Zero
Disaster Recovery
AD Recycle Bin
System Restore
DSRM Tested

Enterprise Security

Hierarchical OUs and strict group delegation.

Group Policy (GPO)

Automated endpoint configuration for seamless user experience.

Architecture Docs

Explore the complete Active Directory setup documentation.

Directory Graph

corp.local structure

IT Admins Group
Full Control · Domain Admins
HR Specialists Group
Read/Write HR$ · Read Public$
Standard Users Group
Read Public$ · Restricted Access
Interactive graph available on wider screens.