HttpWatch supports a number of different file formats for saving the results from a recorded session. The choice of file format depends on the features and interoperability you require with other platforms and tools.

HWL - HttpWatch Native File Format (.hwl)

This is the default file format used by HttpWatch to save and load log files. If you are only going to open the log files in HttpWatch Studio or use them through automation this is the preferred format for the following reasons:

• It has the smallest file size when including content and request bodies
• HWL allows the interchange of full, detailed log files between the Basic and Professional editions of HttpWatch
• It supports and maintains all the information in the recorded log, e.g. service worker responses, HTTP/2 usage, masked fields, etc
• HWL loads and saves faster than other formats

HAR - HTTP Archive File Format (.har)

The HTTP Archive format uses JSON and was originally designed by collaboration between the HttpWatch and Mozilla development teams. It is now supported in all major browsers and most network monitoring tools. It therefore offers interchange between many different platforms and tools. The data within the file can be easily accessed using the JSON support available in most programming languages. The downsides of this format compared to HWL are:

• Larger file size and slower loading
• The format was designed in 2009 and has not been updated since then to reflect changes such as the use of HTTP/2

Also, there are some significant differences in the HAR implement across tools and browsers that sometimes prevents a HAR file from being loaded in one tool after being recorded in another.

CSV - Comma Separated Variables (.csv)

The CSV export format can be customized to contain almost any data field displayed by HttpWatch or can simply be based on the columns selected for display in the main request grid. The format is useful if you just want to view certain data items in Excel or have a simpler file format to import into other tools.

HttpWatch log files cannot re e-loaded from CSV.