CFAPI Specialist

We are seeking an experienced **CFAPI Specialist** with deep, hands\-on expertise in Microsoft's Windows Cloud Files API (CFAPI) and the development of cloud\-based file synchronization solutions. This position requires a specialist who has designed, developed, debugged, and maintained Windows file sync clients—not merely a general C\# or Windows application developer.

The ideal candidate will have strong proficiency in C\#, Windows APIs, P/Invoke, native interop, asynchronous programming, multithreading, and Windows file\-system concepts. The candidate should have practical experience implementing cloud\-backed files, placeholder management, on\-demand file hydration and dehydration, synchronization state management, and reliable communication between Windows clients and cloud storage services.

You will be responsible for building robust, scalable, and high\-performance file synchronization capabilities, troubleshooting complex file\-system issues, and ensuring reliable synchronization across local Windows environments and remote storage platforms.

• *Key Responsibilities:\-**

1\. Windows Cloud Files API (CFAPI) Development

• Design, develop, and maintain Windows\-based file synchronization clients using Microsoft's Cloud Files API.
• Implement and manage Sync Root registration, connection lifecycle, synchronization callbacks, and cloud\-backed file operations.
• Work extensively with CFAPI functions, including:
• CfRegisterSyncRoot
• CfConnectSyncRoot
• CfCreatePlaceholders
• CfExecute
• CfHydratePlaceholder
• CfDehydratePlaceholder
• CfSetPinState
• CfSetInSyncState
• Implement placeholder creation, metadata management, hydration and dehydration workflows, and synchronization state transitions.
• Develop and maintain callback handlers for operations such as FETCH\_DATA and FETCH\_PLACEHOLDERS.
• Implement pinning and unpinning functionality to manage local file availability and cloud\-backed storage behavior.
• Ensure correct handling of callback execution, request completion, cancellation, and error conditions.

2\. Cloud Storage and File Synchronization

• Build reliable synchronization mechanisms between Windows clients and cloud\-based storage or backend services.
• Implement on\-demand file access, remote content retrieval, local file availability, and synchronization status updates.
• Handle file uploads, downloads, metadata synchronization, and synchronization conflict scenarios as required.
• Ensure consistency between local file\-system states and remote storage metadata.
• Design mechanisms for retry handling, recovery from interrupted operations, and synchronization resumption following network or application failures.
• Integrate file synchronization components with REST APIs and cloud storage services.

3\. C\#, Windows APIs, and Native Interoperability

• Develop production\-grade applications and services using C\# and the .NET ecosystem.
• Integrate managed code with native Windows APIs using P/Invoke and interoperability techniques.
• Work with native data structures, delegates, callbacks, handles, memory management, and API error codes.
• Diagnose issues arising from managed/native boundaries, resource management, and API lifecycle handling.
• Apply sound software design principles to develop maintainable, testable, and reliable Windows client components.
• Collaborate with engineering teams on API contracts, architecture decisions, and implementation strategies.

4\. Windows File\-System Internals

• Apply a strong understanding of Windows and NTFS file\-system behavior to file synchronization development.
• Troubleshoot file locking, sharing violations, access permissions, open handles, reparse points, and file operation failures.
• Understand placeholder behavior, file attributes, directory enumeration, file metadata, and file\-system state transitions.
• Investigate issues involving concurrent file access, hydration failures, interrupted operations, and local\-versus\-cloud state inconsistencies.
• Ensure synchronization operations behave reliably under real\-world Windows usage conditions.

5\. Asynchronous Programming and Concurrency

• Design asynchronous workflows for file hydration, content retrieval, synchronization callbacks, and background operations.
• Implement multithreaded processing with appropriate synchronization primitives and thread\-safety controls.
• Handle cancellation tokens, timeouts, retries, race conditions, deadlocks, and resource contention.
• Ensure callbacks and asynchronous operations complete within the required lifecycle and API constraints.
• Optimize concurrent file operations without compromising data integrity or application stability.

6\. Troubleshooting, Debugging, and Performance Optimization

• Investigate complex synchronization failures, placeholder errors, file access issues, and connectivity\-related defects.
• Perform root\-cause analysis using application logs, diagnostic tools, debugger traces, and Windows system information.
• Use Visual Studio debugging and, where appropriate, WinDbg to diagnose application crashes, hangs, and native interop issues.
• Analyze performance bottlenecks in file enumeration, hydration, metadata processing, and synchronization workflows.
• Improve throughput, responsiveness, memory usage, resource utilization, and recovery behavior.
• Develop preventive fixes and regression tests to reduce recurring production incidents.

7\. Testing, Code Quality, and Production Support

• Develop unit, integration, and end\-to\-end tests for CFAPI components and synchronization workflows.
• Validate placeholder lifecycle operations, file state transitions, network interruption recovery, and concurrency scenarios.
• Participate in architecture reviews, code reviews, technical documentation, and engineering design discussions.
• Maintain existing production applications through defect resolution, performance tuning, and reliability improvements.
• Support releases, investigate production incidents, and collaborate with QA, backend, and infrastructure teams.
• Document technical designs, known limitations, troubleshooting procedures, and operational guidelines.

Mandatory Skills and Qualifications

Candidates must have demonstrable, hands\-on experience in the following areas:

• **Professional Experience:** 7–8\+ years of software development experience, preferably focused on Windows desktop applications, system\-level development, or file synchronization products.
• **CFAPI Expertise:** Practical experience developing applications using Microsoft's Windows Cloud Files API.
• **CFAPI Functions:** Working knowledge of Sync Root registration and connection, placeholder creation, callback handling, hydration/dehydration, pin\-state management, and synchronization state updates.
• **File Synchronization Solutions:** Proven experience building or maintaining cloud drive clients, file sync engines, or cloud\-backed Windows file systems.
• **C\# and .NET:** Strong programming skills in C\# and experience developing reliable, production\-grade Windows applications.
• **Windows APIs:** Hands\-on experience with Windows APIs, native interop, and Windows\-specific application behavior.
• **P/Invoke and Interoperability:** Practical experience integrating managed C\# code with native Windows functions and data structures.
• **Windows File\-System Concepts:** Strong understanding of NTFS, file handles, file locking, reparse points, file attributes, and access permissions.
• **Asynchronous Programming:** Experience with asynchronous workflows, task\-based programming, cancellation, exception handling, and reliable background operations.
• **Multithreading and Concurrency:** Ability to diagnose and resolve race conditions, deadlocks, thread\-safety issues, and concurrent file access problems.
• **Debugging and Troubleshooting:** Strong diagnostic skills using Visual Studio and Windows debugging tools to resolve complex production issues.
• **Cloud Storage Integration:** Experience integrating Windows clients with cloud storage platforms, backend services, or REST APIs.
• **Software Engineering Practices:** Proficiency in version control, code reviews, automated testing, documentation, and production support.

• *Important:** This is a specialized CFAPI engineering position. Candidates with only general C\#, .NET, Windows desktop development, or API development experience—but no practical CFAPI or cloud file synchronization experience—may not be suitable.

Good\-to\-Have Skills

• Experience developing OneDrive\-like cloud drive applications or enterprise file synchronization clients.
• Familiarity with Windows Shell integration and File Explorer experiences.
• Experience with C\+\+, Win32 programming, and native Windows debugging.
• Knowledge of Windows Services and background processing architectures.
• Experience with WinDbg, dump analysis, and advanced crash diagnostics.
• Understanding of file\-system notifications and change tracking.
• Experience designing synchronization conflict resolution and recovery mechanisms.
• Exposure to distributed systems, large\-scale Windows client applications, and enterprise cloud storage platforms.
• Experience with performance profiling, memory diagnostics, and reliability engineering.

Pay: ₹1,600,000\.00 \- ₹2,000,000\.00 per year

Application Question(s)

• Do you have hands\-on experience with P/Invoke, Windows/NTFS file\-system concepts, asynchronous programming, multithreading, and debugging tools such as Visual Studio or WinDbg?
• Have you developed or maintained a cloud drive or file synchronization solution using CFAPI?
• How many years of hands\-on experience do you have with Microsoft's Windows Cloud Files API (CFAPI), C\#, and Windows APIs?
• What is your current CTC and expected CTC per annum (in LPA)?
• What is your current notice period, and how soon can you join?

Education

• Bachelor's (Required)

Experience

• CFAPI Specialist – Windows Cloud Files API: 7 years (Required)

Work Location: In person