Open FCS files in your browser
The file every flow cytometer writes, from BD, Beckman Coulter, Cytek and Sony. Open one right here as a table of its events, with no FlowJo. Nothing leaves your device.
Or drop it anywhere on this page
What you'll see
Your FCS file opens as a row for each event and a column for each parameter, named as the cytometer named it.
- A row for each event • A column for each parameter
- Sort and filter • Counts for every column
- Show details • The cytometer, each parameter, the spillover and every keyword
- Export • Save as CSV, Excel, JSON or Parquet
About FCS
The Society for Analytical Cytology, now ISAC, set down the Flow Cytometry Standard in 1984 so data from any cytometer could be analyzed anywhere. Versions 2.0, 3.0 and 3.1 are what cytometers from BD, Beckman Coulter, Cytek, Sony and Thermo Fisher write, and FlowJo, FCS Express and flowCore read.
An FCS has a short header, a TEXT segment of keywords, such as $CYT for the cytometer, $PnN and $PnS for each parameter's name and stain and $SPILLOVER for the compensation matrix, then the DATA: each event, usually a cell, as one value for each parameter, its forward and side scatter, every fluorescence channel and the time, in integers or floats.
Filepeek reads it in your browser into the table viewer: a row for each event and a column for each parameter, named as the cytometer named it with its stain under the name, the values exactly as stored, read in pieces so millions of events open. Sort, filter and count any column, Show details lists the cytometer, the run, each parameter's range, gain and voltage, the spillover matrix and every other keyword, and Export saves the events as CSV, Excel, JSON or Parquet.
Flow Cytometry Standard file
.fcs
Format
- MIME type
- application/vnd.isac.fcs
- Made by
- ISAC, the International Society for Advancement of Cytometry
- Released
- 1984
Inside the file
- Keywords
- The cytometer, the run and each parameter
- Events
- A value for each parameter
- Values
- Integers, floats or doubles
- Versions
- FCS 2.0, 3.0 and 3.1
Opens in every browser
Filepeek opens FCS files in Chrome, Edge, Firefox and Safari, read in pieces so millions of events open at once. On their own, browsers only download them.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Apps that open FCS
- WindowsFlowJo and FCS Express, both paid
- MacFlowJo and FCS Express, both paid
- iPhone and iPadNo app opens it
- AndroidNo app opens it
Questions
How do I open an FCS file without FlowJo?
Drop it on this page or choose Peek an FCS. Its events open in your browser as a table, with every parameter and keyword, on a phone too.
Can I turn an FCS file into CSV?
Yes. Choose Export, then Save as CSV or Excel, with a row for each event and a column for each parameter, the values as the cytometer stored them.
Are the values compensated?
No. They show as the cytometer stored them, and the spillover matrix it saved is in Show details for an analysis app to apply.
Can it draw dot plots and gates?
No. Filepeek shows the events, their parameters and keywords as a table, to sort, filter and save, and FlowJo or FCS Express draw plots and gates.