Freelance Senior Copywriter, Platform + Systems Focus

We’re looking for a Freelance Senior Copywriter to help build and evolve a scalable, user-first copy system within an digital platform. This is not a campaign-driven role. Instead, you'll focus on creating and maintaining thoughtful, consistent messaging frameworks that shape how users interact with the brand in product experiences.

You bring a strategic mindset, deep platform experience, and a collaborative spirit to everything you do. You’ve developed copy systems, voice guidelines, and scalable messaging frameworks before—and you’re energized by the opportunity to shape the user experience through thoughtful, precise language. You’ll work closely with partners across UX, design, strategy, and product to define and implement systems that serve both user and business needs.

You’ll support copy efforts across core product touchpoints, mentor creatives, and bring clarity and structure to a fast-moving platform environment. You understand how to build trust with cross-functional partners, and how to scale language to meet the demands of an evolving product ecosystem.

You Will:

• Develop and evolve in-app copy systems that serve product experience, platform consistency, and brand voice.

• Create scalable, modular copy solutions that can flex across multiple user journeys and touchpoints.

• Partner closely with UX, product design, and content strategy to build cohesive messaging frameworks.

• Contribute to and uphold voice and tone guidelines across user flows, error messaging, transactional copy, onboarding, and notifications.

• Translate complex concepts into clear, concise, user-friendly language.

• Present copy system thinking to clients and internal stakeholders, providing rationale and context for language decisions.

• Collaborate with cross-functional leads including design, product, strategy, and project management to ensure seamless integration of copy into product workflows.

• Champion clarity, consistency, and usability in all written communication.

You Have:

• 5 + years of experience in copywriting, with a strong focus on digital platforms and product environments.

• Demonstrated experience building copy systems, voice guidelines, and messaging frameworks—ideally for apps or complex user flows.

• A deep understanding of UX writing, microcopy best practices, and platform constraints.

• The ability to balance brand voice with clarity, usability, and user needs.

• Experience working in multidisciplinary teams, especially with UX and product design.

• Strong communication and presentation skills, with the ability to articulate your thinking to both creatives and non-creatives alike.

• Excellent attention to detail and a commitment to quality and consistency.

• A calm, solutions-oriented approach in fast-paced, iterative environments.

Critical Mass is an equal opportunity employer. 

The Critical Mass Talent Acquisition team will only communicate from email addresses that use the URLs criticalmass.com and us.greenhouse-mail.io. We will not use apps such as Facebook Messenger, WhatsApp, or Google Hangouts for communicating with you. We will never ask you to send us money, technology, or anything else to work for our company. If you believe you are the victim of a scam, please review your local government consumer protections guidance and reach out to them directly.

If U.S. based: https://www.consumer.ftc.gov/articles/job-scams#avoid
If Canada based: https://www.canada.ca/en/services/finance/consumer-affairs.html
If U.K. based: https://www.gov.uk/consumer-protection-rights
If Costa Rica based: https://www.consumo.go.cr/educacion_consumidor/consejos_practicos.aspx