Using the In-Memory storage

  • Navigate to your Firely Server working directory

  • Changing a setting means overriding it as described in Changing the settings.

  • Find the Repository setting:

    "Repository": "Memory",
  • If it is not already set to Memory, do so now.

  • You can set SimulateTransactions to “true” if you want to experiment with FHIR transactions. The In-Memory implementation does not support real transactions, so in case of an error already processed entries will NOT be rolled back:

    "MemoryOptions": {
        "SimulateTransactions": "true"

Using the In-Memory storage for the Administration API database

This works the same as with the normal Firely Server database, except that you put the settings within the Administration section


"Administration": {
    "Repository": "Memory",
    "MemoryOptions": {
        "SimulateTransactions": "false"


Using the In-Memory storage for the administration layer will cause Firely Server to load the specification files on each startup. This takes several minutes, and Firely Server will respond with a ‘423 - Locked’ error to all requests during that time. As of version 0.7.1 we have implemented support for SQLite, which we recommend to use instead of the In-Memory storage. See Prefer SQLite for Firely Server Administration for more information.