How to Open a QuantStudio .eds File Without the Software

A QuantStudio .eds file is not the sealed binary it looks like. Rename it to .zip and open it, and you will find a folder called apldbio/sds containing the plate setup as XML, the thermal protocol, the raw fluorescence per cycle, and, if the run was analyzed before it was saved, a tab-separated text file with the Ct of every well and detector. That last file is the whole reason you wanted the software.

This matters when the instrument is in a core facility, the software license is on one Windows machine across campus, and a collaborator just emailed you the .eds from a run you need numbers from today.

What is inside an .eds file

Unzip it and look in apldbio/sds/:

• experiment.xml: run name, operator, instrument type, start and end time, the list of samples.
• plate_setup.xml: the plate layout. Each well's samples, detectors (your targets), task (unknown, standard, NTC) and standard concentrations.
• tcprotocol.xml: the thermal cycling program, including the number of cycles.
• analysis_result.txt: the results table. One row per well per detector: a 0-based well index, sample name, detector, Ct, mean Ct, Ct SD, quantity, amplification status and Cq confidence, followed by the Rn and ΔRn values for every cycle.
• filterdata.xml and multicomponentdata.xml: raw and dye-deconvolved fluorescence. Large, and only useful if you want to redraw amplification curves.
• quant/*.quant: the per-well, per-dye fits.

The Manifest.mf at the top names the writer, for example QuantStudio 3 and 5 Software 1.5.2. Files written by StepOne and 7500 software share the layout.

Reading the Ct table by hand

Three things trip people up in analysis_result.txt.

The well column is an index, not a position. 0 is A1, 11 is A12, 12 is B1, and so on, row by row across a 96-well plate (12 columns) or a 384-well plate (24 columns, which plate_setup.xml tells you). Well 62 on a 96-well plate is F3.

Undetermined is written as the last cycle. A well that never crossed threshold on a 40-cycle run has a Ct of exactly 40.0, with the amplification status column showing -1. The desktop software displays that as "Undetermined." If you average those 40s into a group mean you will get a wrong answer that looks plausible, which is the worst kind.

The Task column says "Target" for everything. The real task per well and detector, whether it is an unknown, a standard, or an NTC, lives in plate_setup.xml under the detector-task feature, along with each standard's concentration.

With those three rules a short script turns the file into a tidy table of well, sample, target and Ct. The Rn values and Delta Rn values lines that follow each row are the amplification curve, one value per cycle, if you want to check a suspicious well's shape.

Or skip all of that

VoilàPCR reads .eds files directly as of October 2026. Drop the file in, and the parser unzips it in your browser, finds the results table, converts well indexes to plate positions, treats last-cycle Ct values as undetermined, pulls tasks and standard concentrations from the plate setup, and hands you the same reference-gene and control-group choices a spreadsheet export would. Nothing is uploaded; the unzipping happens on your machine.

One requirement: the run has to have been analyzed and saved in the QuantStudio software at some point, or the archive has no analysis_result.txt and there is no Ct to read. A file saved straight off the instrument before anyone clicked Analyze contains raw fluorescence only. In that case open it in Design & Analysis once, analyze, save, and the file is good from then on. VoilàPCR tells you which case you have.

The same applies to Bio-Rad's .pcrd, which is encrypted and genuinely cannot be opened outside CFX Maestro. If you work with both instruments, the .eds is the one you can read yourself; the .pcrd needs an export or an RDML save from Maestro.

If there is an .eds sitting in your inbox right now, it will analyze in the time it takes to find the reference gene in the list. The first analysis on your own data runs without an account.