In Cyclad, we collaborate with top international IT companies to enhance their capabilities in delivering outstanding, cutting-edge technologies that shape the future world.We are looking for a highly experienced Senior / Lead Developer who has a deep understanding of both technology and the business side of email marketing and performance marketing. The ideal candidate has at least 10 years of experience, excellent command of PHP, and hands-on experience with JavaScript, Python, large-scale databases, mailing tools (SARE, Elastic Email, other ESPs), API integrations, and mass mailing systems. This role requires strategic, analytical, and business-oriented thinking, as well as the ability to respond quickly to technical issues and coordinate activities in a high-scale, production-critical environment. Project information: Location: Warsaw Work Setup: Remote or hybrid work Employment type: Contract of employment / B2B Rate: 1150 PLN/net/Day + VAT Start date: depending on candidate availability  Project scope: Design, develop, and maintain systems for mass email delivery, integrations, and processing large volumes of data (PHP / JavaScript / Python) Manage and administer OVH environments (dedicated servers, VPS, DNS, backups) Work with and administer Assembla repositories, including version control, code reviews, and CI/CD pipelines Integrate with ESPs such as SARE, Elastic Email, SendGrid, Mailgun, or similar email platforms Configure, monitor, and optimize mass email campaigns (scheduling, throttling, IP warm-up, sender reputation) Design and maintain automation processes (CRON jobs, webhooks, ETL processes, workflows) Work with large databases (MySQL / PostgreSQL), including: deduplication, data corrections, and sanity checks data cleansing and segmentation mechanisms query and index optimization backup and data recovery mechanisms Monitor email deliverability (SPF, DKIM, DMARC, domain reputation, bounce management) Respond to incidents and technical issues in real time (alerts, sending errors, integration/API failures) Build tools to automate marketing and performance workflows Design integrations with CRM/CDP systems, advertising platforms, and analytics tools Collaborate closely with marketing, data, and business teams to translate campaign objectives into technical solutions Mentor team members, perform code audits, and co-design system architecture Requirements: Minimum 10 years of experience as a software developer and/or system architect Proven experience handling large-scale email delivery (millions of emails per day) Expert-level knowledge of PHP (Symfony) in production environments. Strong proficiency in JavaScript and Python (automation, scripting, pipelines) Hands-on experience with OVH infrastructure, including configuration and maintenance Experience with Assembla or similar repository and project management systems Deep expertise in email marketing technologies and processes, including: SARE, Elastic Email, SendGrid, Mailgun (or similar ESPs) delivery mechanisms, throttling, IP warm-up deliverability and DNS (IMAP, SMTP SPF / DKIM / DMARC) tracking and measurement systems Strong knowledge of MySQL / PostgreSQL, including: record deduplication optimization of large tables backups, replication, and data recovery Experience designing and maintaining API integrations (REST / GraphQL) and automated workflows Excellent analytical skills with the ability to combine technical and business perspectives Strong collaboration, communication, and mentoring skills Ability to quickly diagnose and resolve issues in production environments Knowledge of GDPR and data security best practices for email marketing We offer: Competitive compensation with flexible engagement models (employment contract or B2B) Real influence on architecture, processes, and technology in a key business area Work on large-scale data platforms and projects with direct business impact Access to modern tools, a professional development budget, and innovative technologies Flexible remote or hybrid working model Collaboration with experienced professionals in marketing, technology, and analytics