Ranbel Sun

Technical writing portfolio

Developer documentation, user manuals, and training resources

Cloudflare Tunnel Kubernetes tutorial

Context

The legacy documentation relied on a locally managed configuration workflow that was no longer recommended for new deployments. Additionally, the old guide only provided a sample YAML file with minimal context and no step-by-step deployment instructions. The goal was to create a detailed tutorial for deploying tunnels using Cloudflare's modern remotely managed workflow.

My role

I independently researched the new remotely managed workflow by spinning up a Kubernetes lab environment. I mapped out the architecture, created the diagram in Figma, and authored the new guide — including writing, validating, and testing the YAML manifests and CLI commands.

Impact

The new tutorial steered users away from complex legacy setups towards the remotely managed deployment pattern. Additionally, this work directly addressed long-standing community feedback on GitHub requesting more detailed Kubernetes documentation.

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"Replace Your VPN" implementation guide

Context

Enterprise customers migrating away from legacy VPNs lacked a clear, comprehensive guide for adopting Zero Trust Network Access (ZTNA). Internal subject matter experts (SMEs) provided a dense text draft covering deployment best practices and high-level steps.

My role

I transformed the raw SME draft into a structured, digestible learning path. I designed the visual architecture diagrams and authored several conceptual sections from scratch based on bullet points. To accommodate enterprise teams utilizing Infrastructure-as-Code (IaC), I also introduced and validated Terraform configuration blocks.

Impact

The guide quickly became a core enablement asset. Solutions Engineers distributed it to prospects to accelerate VPN replacement POCs. Additionally, the Cloudflare One Client engineering team adopted the guide as a standard onboarding resource for new hires.

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Common Access policies reference guide

Context

Based on customer feedback, users frequently struggled to translate complex identity and network access conditions into valid code configurations. No centralized cookbook existed for these common policy patterns, and LLM/coding assistants often hallucinated incorrect API calls.

My role

I audited internal wikis to extract the most common access control use cases. I then created a centralized reference guide, independently writing and verifying the specific REST API payloads and Terraform resource blocks required to execute them programmatically.

Impact

The guide provided developers with practical policy examples vetted by Cloudflare implementation teams. Additionally, adding authoritative API and Terraform examples grounded AI agents, allowing them to accurately design and deploy policies to user accounts.

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Multiplexer hardware user manual

Context

To support the launch of a new industrial multiplexer board, the product required a comprehensive user manual created from scratch.

My role

As the sole technical writer at the company, I wrote and illustrated the manual from start to finish. On the hardware side, I operated electrical test equipment like oscilloscopes and signal generators to physically validate common user workflows, while translating raw engineering schematics into clean vector wiring diagrams. On the software side, I wrote and tested sample code blocks for two developer tiers: high-level object-oriented frameworks (C++) and low-level direct driver access (C).

Impact

The manual was completed well ahead of the official product launch. Providing clear wiring diagrams alongside ready-to-use sample code allowed customers to immediately integrate the hardware into their systems.

Download manual (PDF) →

Introductory quantum computing textbook

Context

In 2018, most educational resources for quantum computing sat at extreme ends of a spectrum: either oversimplified popular science articles or dense academic textbooks. Backed by a National Science Foundation (NSF) grant, the goal of this project was to bridge this gap by developing rigorous yet accessible quantum computing educational resources for high school students.

My role

Working with Fermilab researchers, I designed the curriculum outline, information architecture, and pedagogical scope for the entire textbook. I authored and illustrated roughly 80% of the published manuscript, translating abstract quantum mechanics principles into structured learning modules. To support active learning, I also developed problem sets, simulation-based demos, and IBM Q lab exercises.

Impact

The book was published internationally through Springer and has received over 400,000 downloads. It serves as a free educational resource for schools looking to introduce quantum literacy into their advanced STEM programs.

View ebook →