Mohan is one of those rare finds who has both outstanding technical and communications skills. (Do a Google search on "Mohan Embar" if you have a moment.) For the last fourteen years he has been the primary payments and PCI compliance engineer at Ontraport, sole author of the software at the heart of the platform's PCI DSS Level 1 certification and core maintainer of the multithreaded C++ engine that delivers millions of emails per day. He won the 2012 Loebner Prize in artificial intelligence with a chatbot he built from scratch, contributed 50+ patches to GCC, and has consulted for companies such as Northwestern Mutual, Bloomberg, France Telecom, Société Générale, Cyco Software and Kraft. Born and bred in Chicago, he has lived and worked in Europe and speaks eleven languages.

Intro Page | LinkedIn

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Technical Skills

Languages
Currently: C++, PHP, Lua, SQL (PostgreSQL, MySQL), Bash
Throughout my career: Java, C#, C, Objective-C
During my former lives: Delphi, Pascal, BASIC (+WordBasic), dBASE, Assembler (80x86, 68000, Z-80), PL/I, plus academic FORTRAN, COBOL, LISP, PROLOG.

Infrastructure & data: PostgreSQL, MySQL, Redis (caching, Redlock distributed locking, write aggregation), AWS, Kubernetes/Helm, Docker, OpenResty/nginx

Specialties: payments systems and gateway integrations (Stripe, PayPal, Authorize.Net, eWay…), PCI DSS compliance, applied cryptography, multithreading and concurrency, near-zero-downtime database migrations, AI-assisted engineering with verification-first workflows

Work Experience

(see also Open Source, Personal Projects and Distinctions)

ONTRAPORT (2012 - present)

Senior Backend Software Engineer (remote)

Ontraport is a marketing-automation SaaS platform (CRM, email, e-commerce, payments) based in Santa Barbara, CA. I am the primary engineer for payments and PCI compliance:

  • Sole author of the software at the heart of the platform's PCI DSS Level 1 certification — an OpenResty/Lua tokenization layer that strips raw card data from inbound traffic, a C++ card-data cache, and the PHP payments application — isolating cardholder data from the general-purpose infrastructure. (The certification itself was a cross-team effort; infrastructure and ops own the running stack.)
  • Designed the cryptography and key-splitting scheme protecting stored card data; own the recurring key-rotation and card-data lifecycle operations.
  • Built a C++ in-memory card-caching server that speaks the Redis wire protocol, so clients integrate with off-the-shelf Redis libraries.
  • Designed a PCI-compliant iframe card-field isolation service (2025) and built its backend and REST API: HMAC request verification, distributed nonces, HTML sanitization, sub-100ms responses. (In-page frontend built with a colleague.)
  • Maintain the payment-gateway integrations: Stripe, PayPal (Standard and Website Payments Pro), Authorize.Net, eWay/eWay Rapid, and others.
  • Wrote the audit-facing documentation for the PCI assessments — data-flow diagrams, architecture and narrative docs — most recently produced with AI under my direction.
  • Core maintainer of the multithreaded C++ email engine that delivers millions of messages per day: job queues, thread pools, atomic stats aggregation, race-condition hunting.
  • Key engineer on the platform's migration to AWS: wrote the payments services and the Docker image and Helm chart definitions for the new AWS environment — certified in the 2026 PCI DSS Level 1 assessment — working alongside the infrastructure team that owns the running stack.
  • Retooled the PCI payments codebase to run bilingually against MySQL and PostgreSQL behind a common database layer, and built phased live-sync tooling for near-zero-downtime migration of the live payments database — having executed a trivial-downtime payments-database move once before.
  • Instituted the company's unit-test methodology; heavy production use of AI coding agents under a verification-first workflow.

Environments: PHP, C++, Lua, PostgreSQL, MySQL, Redis, AWS, Kubernetes

Earlier Career (highlights)

NTT Data (2017) - Replaced the Access database of a massive mid-90s C++ codebase with an ODBC-emulation layer over in-memory/read-only-file storage, turning a single-machine process into one serving many concurrent clients.

CTO, Docudesk Corporation (2011-2012) - Led development of commercial PDF products; wrote the Cocoa Mac version of deskPDF Creator from scratch. Earlier (2006-2009), designed and built their commercial Java/native PDF-to-Word converter for Windows and OS X, including custom gcj compiler builds.

Cofounder, MODA Interactive (2011-2012) - Sole developer of shipped Mac, Windows and iOS products (PandaTunes, PandaRemote, Num-Num).

RhinoSoft.com (2010-2011) - C++/MFC desktop application: multithreading, networking protocols, session pools.

Northwestern Mutual Life (1997-2005) - My longest engagement; they called me "The Jackknife" because I could tackle almost anything. Co-created the C++ and Java application frameworks that powered hundreds of internal applications company-wide, helped institutionalize that knowledge into the Engineering Competency Center, and mentored dozens of developers. Highlights: a Smalltalk-to-C++ code translator, an MQ C++ emulation library over Win32 shared memory, a distributed page-generation framework, Blowfish ports to Java and C#, and a massive RogueWave/HP-UX upgrade where I underbid and outperformed offshore consultants despite my higher billing rate.

Before that: Bloomberg (NYC, Equities) and Deluxe Data Systems in the US; Forsk (subcontracting for France Telecom, working in French) and doctoral research in machine translation in France; Cyco Software in the Netherlands; consulting for Kraft to pay my way through college.

Open Source, Personal Projects and Distinctions

Chip Vivant: Winner, 2012 Loebner Prize

I wrote Chip Vivant completely from scratch — custom forward- and backward-chaining reasoning engines, a hand-built commonsense database, and interfaces to Wordnet, OpenCyc, ConceptNet, Wikipedia and Wiktionary — and won first place in the 2012 Loebner Prize Contest. Chip could authoritatively answer commonsense questions like whether an orange is bigger than the moon, and follow conversational sequences like "The blue bottle is on the table. / Where is the bottle? / What color is the bottle?" — years before large language models made that look easy.

GNU Compiler Collection (gcj)

50+ accepted patches to the Java front end and class libraries, focused on the Win32 port; earned CVS write access. If you read the official GCC 3.4 release notes and find the sentence beginning "Enhancements include socket timeout support…" — I both wrote that sentence and built every enhancement in it.

The Renaissance Software Engineer's Guide to Learning a Foreign Language

I wrote a book-length guide to foreign-language learning for software engineers: youcanlearnthatlanguage.com.

Languages (the human kind)

English (native) · Dutch, French (C2) · Spanish, Italian (C1) · Portuguese, Swedish, Russian, German (B2) · Turkish (B1) · Vietnamese (A2) · currently learning Greek

Education

Carnegie-Mellon University (Pittsburgh, Pennsylvania)

B.S., Applied Mathematics (Computer Science)

Ecole Polytechnique Fédérale de Lausanne (Switzerland)

Third-year exchange program by special admission; studies completely in French.

Additional

US citizen; eligible to live and work in the EU (Dutch spouse). Remote-first since 2012. One of a handful on the company-wide 24/7 PagerDuty rotation for 13+ years.

Intro Page