Several optional features can be purchased to extend the power and functionality of the free WaveViewer:

WaveFormer Pro with Pattern Generator Support:

In addition to being a great waveform viewer, WaveFormer Pro supports over 55 different formats for importing and exporting waveform data. Import waveform data from simulators, logic analyzers, and timing analysis programs. Export waveforms to VHDL, Verilog, SPICE, Pattern Generators, ATE, and FPGA tools. WaveFormer Pro is also a full timing diagram editor, so you can create specification diagrams and analyze timing.

GigaWave Feature:

The GigaWave feature converts WaveViewer into GigaWave Viewer, a high capacity waveform viewer capable of handling multi-gigabyte VCD files. Without GigaWave, WaveViewer is limited to diagrams of less than 10,000 signals and less than 1 million waveform state changes. The GigaWave feature also comes with a PLI-based library that can be integrated with your favorite simulator to directly generate highly compressed BTIM files (no intermediate dump to VCD is required). Using direct BTIM waveform dumping can speed up simulation by up to 3x compared to the same simulation using an ordinary VCD dump because of the reduction in file I/O, and the resulting files are generally 200x smaller.

Waveform Comparison Feature:

The Waveform Comparison feature lets users compare waveforms for two timing diagrams or individual signals. This feature is particularly useful for comparing two different simulation runs, as well as for comparing logic analyzer data to a simulation run. The specific regions where waveforms differ will turn red when two waveforms are compared.  In addition to standard waveform comparison, where all differences are detected, the comparison feature also supports "Clocked comparison" where waveforms are only checked at clock edges. Tolerances can also be specified to determine what constitutes a significant difference between two waveforms. For more information on using the Waveform comparison feature, please refer to Chapter 9 of the Timing Diagram Editor Manual.

Transaction Tracking Feature:

The Transaction Tracking feature lets users view waveform data as "transactions" instead of as just signals. The user specifies PSL Sugar expressions that describe what transactions to search for, and the transaction tracker search engine finds matching transaction records and displays them graphically in the timing diagram window.