Alok Ranjan (@aloki-alok), a software engineer at OmniDimension. He goes by ryu online. Projects and writing.https://alokranjan.me/https://alokranjan.me/blog/invisible-character-production-bug/https://alokranjan.me/blog/invisible-character-production-bug/A broken PDF font map produced a NUL byte. Every layer accepted it until the database rejected the write, while HTTP 200 made the failure look successful.Sun, 04 Oct 2026 00:00:00 GMTproductionreliabilityjsonpdfdistributed-systemshttps://alokranjan.me/blog/nat-voip/https://alokranjan.me/blog/nat-voip/NAT let the internet outgrow its public IPv4 address supply. It also made a connected VoIP call a surprisingly different problem from a working one.Sun, 23 Aug 2026 00:00:00 GMTnatvoipsiprtpnetworkingtelephonyhttps://alokranjan.me/blog/the-account-was-the-hard-part/https://alokranjan.me/blog/the-account-was-the-hard-part/x402, Cloudflare Wallets and cloudflare.pay are usually described as giving AI agents a wallet. What they actually do is take apart the account: the thing that fuses who you are, what you're allowed to use, and how you pay into one long-lived, human-shaped object.Mon, 10 Aug 2026 00:00:00 GMTx402agentscloudflarepaymentshttpprotocolshttps://alokranjan.me/blog/phone-number-flagged-before-we-used-it/https://alokranjan.me/blog/phone-number-flagged-before-we-used-it/Recycled phone numbers carry the previous owner's spam reputation. We linked out to Truecaller instead of showing our own guess, which meant reverse-engineering an undocumented Android deep link with adb.Thu, 16 Jul 2026 00:00:00 GMTreputationtelephonyandroiddeeplinksadbhttps://alokranjan.me/blog/slow-page-not-the-database/https://alokranjan.me/blog/slow-page-not-the-database/A dashboard page was slow to load, so everyone reached for the database. The real cost was the code drawing one dropdown 400 times. A story about N+1 queries and the fix that took them from 400 to 4.Thu, 16 Jul 2026 00:00:00 GMTperformancen+1ormpostgresbackendhttps://alokranjan.me/blog/email-deliverability/https://alokranjan.me/blog/email-deliverability/An AWS suspension taught me that email deliverability is a reputation system. Here is what actually moves it: bounce thresholds, the hard ceiling on address verification, and why clean lists still land in spam.Sat, 13 Jun 2026 00:00:00 GMTemaildeliverabilitysmtpinfrastructurehttps://alokranjan.me/blog/extending-uptime-kuma/https://alokranjan.me/blog/extending-uptime-kuma/Getting an unmerged feature into production, adding a Slack /incident command, and open-sourcing the result as a clean fork.Sat, 30 May 2026 00:00:00 GMTuptime-kumamonitoringopen sourcedockerhttps://alokranjan.me/blog/omnidimension-mcp/https://alokranjan.me/blog/omnidimension-mcp/Building OmniDimension's MCP integration layer: two services, 49 tools, an OAuth 2.1 server, shipped to npm and live in production.Fri, 29 May 2026 00:00:00 GMTMCPOAuthAI agentsTypeScripthttps://alokranjan.me/blog/computers-dont-know-the-time/https://alokranjan.me/blog/computers-dont-know-the-time/A trip down the rabbit hole of quartz crystals, cesium atoms, GPS, NTP, and PTP, after chrony told me my clock was running slow.Fri, 22 May 2026 00:00:00 GMTsystemstimentplinuxhttps://alokranjan.me/blog/postfix-mail-server/https://alokranjan.me/blog/postfix-mail-server/Configuring a multi-tenant mail server from scratch with Postfix and Dovecot, now handling 200k+ emails a day.Mon, 18 May 2026 00:00:00 GMTpostfixsmtpimaplinuxemailhttps://alokranjan.me/blog/agentic-ai/https://alokranjan.me/blog/agentic-ai/Agentic AI is the same LLM wired into a loop: plan, act, observe, repeat, until a goal is met instead of answered in one reply.Sat, 19 Jul 2025 00:00:00 GMTAI agentsLLMhttps://alokranjan.me/blog/inv/https://alokranjan.me/blog/inv/A FastAPI service that stores stock prices, serves them over a REST API, and backtests a moving-average crossover strategy, containerized end to end. Two bugs taught me more than the assignment did.Fri, 18 Jul 2025 00:00:00 GMTpythonfastapidockerpostgresqlsqlalchemy