Engineering notes from ProCat Solutions: high-load backends, multi-tenant SaaS, VoIP and telecom, Voice AI, Web3.https://procatsolutions.com/enhttps://procatsolutions.com/en/blog/abigel-ai-is-live/https://procatsolutions.com/en/blog/abigel-ai-is-live/Our DIMOP Plusz project has closed: the phone assistant and the AI language teacher are live at abigel.ai. Lessons on latency, streaming and telephony.Tue, 15 Sep 2026 00:00:00 GMTabigelvoice-aidimop-pluszsaastelephonylanguage-learninghttps://procatsolutions.com/en/blog/abigel-ai-teacher-conversation-based-language-learning/https://procatsolutions.com/en/blog/abigel-ai-teacher-conversation-based-language-learning/How the Virtual Assistant voice pipeline became a language teacher: 26 languages, A1-B2 levels, real-life scenarios, KIDS mode and instant correction.Tue, 08 Sep 2026 00:00:00 GMTabigelteacherlanguage-learningvoice-aillmdimophttps://procatsolutions.com/en/blog/abigel-ai-virtual-assistant-in-practice-sme-reception-in-10-minutes/https://procatsolutions.com/en/blog/abigel-ai-virtual-assistant-in-practice-sme-reception-in-10-minutes/Step by step: sign-up, industry template, the no-code flow, call forwarding with the *61* code, a test call, transcripts, CSV export and the referral program.Tue, 18 Aug 2026 00:00:00 GMTabigelvirtual-assistantvoice-aismephone-receptiondimophttps://procatsolutions.com/en/blog/agent-to-agent-when-ai-agents-talk-to-each-other/https://procatsolutions.com/en/blog/agent-to-agent-when-ai-agents-talk-to-each-other/MCP, tool use, planner/worker and handoff patterns, guardrails, human-in-the-loop, tracing: when a multi-agent system pays off and when a workflow is enough.Tue, 14 Oct 2025 00:00:00 GMTai-agentmcporchestrationllmobservabilityarchitecturehttps://procatsolutions.com/en/blog/we-won-the-dimop-plus-grant/https://procatsolutions.com/en/blog/we-won-the-dimop-plus-grant/Under the DIMOP_PLUSZ-1.1.2/A-24 call we are building a multi-tenant voice AI customer service platform with HUF 14.53 million of funding, until autumn 2026.Tue, 01 Jul 2025 00:00:00 GMTgrantdimop-pluszvoice-aisaascustomer-supporthttps://procatsolutions.com/en/blog/abisearch-vector-search-on-hungarian-documents/https://procatsolutions.com/en/blog/abisearch-vector-search-on-hungarian-documents/The Abisearch vector search API: embeddings instead of keywords, Hungarian morphology, JSON and Excel upload, re-ranking, EU data centre and a free tier.Tue, 18 Mar 2025 00:00:00 GMTabisearchvector-searchembeddingsaasapihttps://procatsolutions.com/en/blog/crypto-trading-and-automation-bots/https://procatsolutions.com/en/blog/crypto-trading-and-automation-bots/Exchange REST and WebSocket APIs, order lifecycle, rate limits, risk controls and monitoring: engineering lessons from building crypto trading bots.Tue, 21 Jan 2025 00:00:00 GMTcryptoweb3websocketnodejsautomationrisk-managementhttps://procatsolutions.com/en/blog/voice-agent-architecture-stt-llm-tts-in-real-time/https://procatsolutions.com/en/blog/voice-agent-architecture-stt-llm-tts-in-real-time/Building a real-time voice AI agent: streaming STT, LLM and TTS, a latency budget, jitter buffers, SIP and WebRTC media, and Hungarian language specifics.Tue, 10 Dec 2024 00:00:00 GMTvoice-aisttttsllmsipwebrtcarchitecturehttps://procatsolutions.com/en/blog/web3-detour-smart-contracts-presales-lessons/https://procatsolutions.com/en/blog/web3-detour-smart-contracts-presales-lessons/A Solidity and OpenZeppelin token presale with whitelist and referrals, gas on Polygon and Arbitrum, an Ethers.js backend, testing, audits and takeaways.Tue, 10 Sep 2024 00:00:00 GMTweb3solidityopenzeppelinetherspolygonarbitrumhttps://procatsolutions.com/en/blog/whatsapp-business-api-and-omnichannel-support/https://procatsolutions.com/en/blog/whatsapp-business-api-and-omnichannel-support/The WhatsApp Cloud API in practice: templates and approval, the 24-hour window, webhooks, a shared inbox with SMS and voice, chatbot flows and GDPR.Tue, 16 Apr 2024 00:00:00 GMTwhatsappomnichannelcustomer-supportchatbotgdprhttps://procatsolutions.com/en/blog/sms-gateway-and-gsm-modems/https://procatsolutions.com/en/blog/sms-gateway-and-gsm-modems/GSM modem pools, AT commands, SIM management, delivery reports, message queues, combining SMS with voice, and when an aggregator is the better choice.Wed, 08 Nov 2023 00:00:00 GMTsmsgsmgatewaytelecommessage-queuehttps://procatsolutions.com/en/blog/voip-sip-and-pstn-bridge-entering-telecom/https://procatsolutions.com/en/blog/voip-sip-and-pstn-bridge-entering-telecom/Our first months with SIP telephony: codecs, NAT and RTP pitfalls, SIP trunks, the PSTN bridge, IVR, call routing, WebRTC and call quality metrics.Tue, 11 Jul 2023 00:00:00 GMTvoipsippstnwebrtctelecomhttps://procatsolutions.com/en/blog/multi-tenant-saas-architecture-in-practice/https://procatsolutions.com/en/blog/multi-tenant-saas-architecture-in-practice/Tenant isolation models, row-level security, per-tenant configuration in the database, migrations, noisy neighbours, billing hooks and backups in a SaaS.Tue, 14 Feb 2023 00:00:00 GMTsaasmulti-tenantpostgresqlarchitecturehttps://procatsolutions.com/en/blog/designing-high-load-rest-apis/https://procatsolutions.com/en/blog/designing-high-load-rest-apis/Node.js and NestJS APIs under production load: PostgreSQL indexing, connection pooling, Redis caching, rate limiting, idempotency and observability.Tue, 20 Sep 2022 00:00:00 GMTrest-apinodejsnestjspostgresqlredisload-testinghttps://procatsolutions.com/en/blog/why-we-founded-an-infrastructure-first-software-company/https://procatsolutions.com/en/blog/why-we-founded-an-infrastructure-first-software-company/The first post from a Budapest micro-company: why we build around infrastructure, secure APIs and high availability instead of feature lists.Tue, 15 Mar 2022 00:00:00 GMTgetting-startedinfrastructurebackenddocker