ProcessActivityView is a portable Windows utility from NirSoft that enables IT professionals and system administrators to analyze the file activity of a specific running process. Unlike global file monitors that capture all file operations system-wide, this tool focuses exclusively on the file and folder interactions of a selected process — making it useful for targeted troubleshooting and forensic analysis of application behavior.
ProcessActivityView provides a summarized view of file activity for a process you choose. For each file accessed, it shows:
Number of open/close operations
Count of read and write calls
Total bytes read or written
The specific DLL that issued the last open-file call
Additional access statistics
This information helps you understand how a process interacts with the file system — essential when diagnosing performance issues, file lock problems, or unintended application behavior.
Process-Focused File Activity Summary — Only file system activities of a selected process are reported.
Detailed Access Counts — Includes how many times a file was opened/closed, read from, and written to.
I/O Volume Metrics — Shows cumulative bytes read and written.
Helper DLL Injection — Internally injects a helper DLL to intercept underlying Windows file I/O API calls.
Portable & Lightweight — No installation or additional libraries required.
Separate 32-bit & 64-bit Versions — Ensures correct behavior depending on target process architecture.
| Component | Description |
|---|---|
| Operating System | Windows 2000 up to Windows 8 (official listing) |
| Architecture | Requires matching 32-bit or 64-bit binary for target process |
| Privileges | Administrator privileges recommended for comprehensive access |
ProcessActivityView works by attaching a small helper DLL (ProcessActivityViewHelper.dll) to a target process. That DLL intercepts internal file I/O operations via Windows API hooks, and reports details back to the main utility. This allows the utility to capture real time operations such as create, read, write, and close calls without monitoring the entire system.
Because it relies on API interception, ProcessActivityView provides summarized statistics rather than full recorded traces — reducing noise and focusing attention on volume and frequency patterns from the selected process.
ProcessActivityView is suitable for:
Debugging file access performance — identify which files a process frequently opens or writes.
Diagnosing file locks or sharing violations (in conjunction with tools like OpenedFilesView).
Security and compliance investigations — understanding whether a process is accessing unexpected files.
Software development and QA — verifying expected file access patterns without full trace logs.
Incident response — targeted examination of suspicious process behavior.
Cost: Freeware — no license fee.
Distribution: Portable executable from NirSoft official website.
Installation: None; simply extract and run.
Visit the official NirSoft download page for ProcessActivityView.
Extract the ZIP file to a local folder.
Run ProcessActivityView.exe matching your system bit-depth (32-bit or 64-bit).
Upon launch, a dialog will prompt you to choose one of the currently running processes.
Select the target process whose file activity you want to monitor.
Click OK to begin data collection.
You will see a table summarizing:
File path
Number of opens/closes
I/O call counts (read/write)
Total bytes transferred
DLL responsible for last open call
Use sorting and filtering on columns to highlight patterns or anomalies.
There are no specific command-line options — ProcessActivityView is GUI-driven. However, examples of interpretation include:
C:\app\data.db OpenCount=12 ReadCount=248 WriteCount=80 BytesRead=1,024,000 BytesWritten=512,000
This entry indicates that the selected process accessed data.db frequently, with heavy read activity compared to writes — potentially useful in diagnosing slow application startup or data loading behavior.
| Issue | Likely Cause | Recommended Fix |
|---|---|---|
| Fails to attach to process | Architecture mismatch (32/64 bit) | Use matching binary for target process |
| Limited data shown | Running with insufficient privileges | Run as Administrator |
| Process crashes when attaching | System service or system process | Avoid tracing system-level protected processes |
| No activity shown | Process idle or inactive | Stimulate process I/O activity and retry |
DLL Injection — Uses a helper DLL to monitor API calls; some endpoint security products may flag this behavior.
Privilege Requirements — Requires elevated access for certain processes; limit use to trusted environments.
Sensitive File Data — Output may reveal access to configuration or personal files; handle reports with appropriate confidentiality.
Always choose the binary version that matches the architecture of the process you want to monitor.
Use in combination with broader system monitors (e.g., Process Monitor, Event Viewer) for context.
Capture and save summaries for after-action reviews or collaboration with development teams.
Limit use on production systems to avoid potential performance impact.
Consider exporting summaries for archival or comparison across sessions.
ProcessActivityView is a specialized lightweight utility for targeted file activity analysis of individual Windows processes. By providing concise summaries of how a process interacts with the file system, it assists administrators and developers in diagnosing performance issues, file dependencies, and unexpected behaviors. As freeware with a portable footprint, it fits into technical troubleshooting workflows where focused insights are needed without the overhead of full system logging.
