Things I've built.

Most knowledge tools surface what you already know to ask for. Vhaeon is built around the connections you didn't think to look for — a 3D knowledge graph for serendipitous discovery via multi-dimensional intersection.

• Vienna 1913 as the north star — what would a tool look like that surfaces the right intersection at the right moment?
• Blank canvas → search → 3D graph → crystallize → resonate → weave
• Semantic axes for time, branch, and depth; info spheres with side panels for controls and neighbors
• AI-assisted navigation via local Ollama integration — chat as a way to remap the graph, not just a sidebar
• Self-hosted, open for exploration, not for sale

AI agents act faster than anyone can supervise, and one bad decision can mean a runaway cost spike, a double refund, or an irreversible call to a downstream system. AgentDelivery puts budget gates, human approvals, idempotent delivery, and instant rollback between an agent's trigger and the action it fires — without changing the agents you already run.

• Budget & rate ceilings — kill runaway loops and cost spikes before any action runs
• Human-in-the-loop approvals — pause any sensitive or irreversible action until a person says yes
• Idempotent delivery — a retry never double-fires (no duplicate refunds or double sends)
• Automatic rollback & immutable audit — undo a bad action; see everything every agent did
• Multi-tenant from line one — tenant isolation, per-tenant rate limiting, signing-key separation as architectural commitments, not retrofits
• Plan model (Free / Starter / Core / Scale / Enterprise), Stripe billing wired end-to-end; Go, Postgres, OTEL, self-hosted on OVH

ROAS, average order value, conversion rate — the metrics most ecom dashboards lead with hide the costs that actually erode margin. Refunds, chargebacks, payment processor fees, VAT, shipping. BillNode shows the numbers that survive once those are accounted for.

• Six margin and billing calculators across two tracks: ecom/DTC operators and freelance/agency
• True net margin, break-even ROAS, fee analysis — all client-side, deterministic, no data sent anywhere
• Single-file static HTML — no framework, no server, no build step. Open in a browser and it works.
• Free to use; designed to be embedded, white-labeled, or operated under a buyer's brand
• Self-hosted on OVH; trivially portable to any static host

Most software-business writing is either war stories from outliers or generic advice that maps to nobody's situation. The New Tradesman is a publication on the recurring failure patterns — billing breakage, support drift, quiet trust erosion — that show up across companies, with judgment and restraint instead of blame.

• Pattern-driven editorial format — each post identifies a failure mode that recurs across software companies
• Anonymized case studies across billing, support, trust, and operational hygiene
• Strict pattern schema per post: name, mechanism, signal, intervention, residue
• Stock Ghost CMS with code-injection analytics (GA4 + Umami in parallel); structured for SEO from day one
• Cross-linked with constantin-works.com per editorial checklist; growing library

Most invoice tools ask you to make an account before you can do anything. PlainStatement skips the ceremony — open it, fill the fields, get the PDF. Paid tiers add saved history, EU VAT validation, share-by-link, payment links, recurring invoices, quotes that convert to invoices, and a tamper-evident audit ledger.

• Free tier: create + download invoices with no account, no card, no email — runs in the browser
• Basic (€50/yr): saved invoices and clients, quotes, share-by-link, EU VAT/VIES validation with reverse-charge clauses, payment links, audit ledger, overdue reminders
• Pro (€100/yr): higher volume limits, automatic reminders, recurring invoices, PDF receipts for paid invoices
• Tamper-evident audit ledger + downloadable audit pack per invoice — unusual at this price point
• VAT-specific surface: dedicated VAT invoice generator, quote generator, freelance invoice generator alongside the main flow
• Express.js + Node, self-hosted on OVH (migrated DO → OVH with PM2 + nginx + Let's Encrypt)
• Built and shipping — operator-ready, looking for a distribution operator rather than only a buyer

Most affiliate plays are either content (drive intent, lose the click) or deals (capture intent that came from somewhere else). The sister sites pair is both — a content site that creates buyer intent paired with a deals site engineered to capture it. Sold bundled by default; designed to feed each other.

• Selling Currently — AI-driven niche content site across commerce verticals. 50+ published articles, SEO-structured, growing. WordPress with REST API automation pipeline.
• Currently Selling — Hand-verified deals on the gear small online sellers (Etsy/Vinted/eBay) actually use: label printers, packaging, lighting, postage scales, software. Astro frontend, Node/Express affiliate redirector, Postgres schema for deals/clicks/price snapshots. Affiliate infrastructure built; deals seeded as drafts pending real partnerships.
• Reciprocal flow by design — content links to deals, deals link back to topical content, same operator runs both

Most retail forex calculators are scattered across broker sites, gated behind signups, or padded with ads. ForexFin is a free, ad-free toolkit for retail traders who want the math right before they click buy — calculators, session and strength tools, a concept library, and a price-alerts engine, all in the browser.

• Eight calculators: position size, pip value, margin, swap, R:R, Kelly, spread cost, and a Trade Plan Builder that combines them
• Currency Strength Meter and Pair Correlation Matrix — basket and cross-market views built from ECB reference rates
• Market-hours visualizer for the major sessions; Learn hub with concept pages for pip, leverage, and margin call
• Price-alerts engine — live, magic-link signup, set a level and get notified when it triggers
• Calculators and tools run client-side and signup-free; alerts use magic-link auth, no password
• Pivoted from B2B fintech webhook demo to retail tools; self-hosted on OVH (PM2 + nginx + Let's Encrypt)