Download of NanoDrop 1000 3.8.1 was on the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The actual developer of the free program is Thermo Fisher Scientific. We recommend checking the downloaded files with any free antivirus. The program lies within Education Tools, more precisely Science Tools. The most popular version among NanoDrop 1000 users is 3.8.
From the developer:
The Thermo Scientific NanoDrop 1000 Spectrophotometer measures 1 ul samples with high accuracy and reproducibility. The full spectrum (220nm-750nm) spectrophotometer utilizes a patented sample retention technology that employs surface tension alone to hold the sample in place. This eliminates the need for cumbersome cuvettes and other sample containment devices and allows for clean up in seconds.
You may want to check out more software, such as NanoDrop, NanoDrop 2000 or Kurzweil 1000, which might be similar to NanoDrop 1000.