---
title: "FastFlags (FFlag, DFInt, FString, FLog) — Bloxstrap & Roblox Technical Glossary"
description: "Engine configuration variables read by RobloxPlayerBeta.exe from ClientAppSettings.json at startup. Learn how FastFlags (FFlag, DFInt, FString, FLog) works in Bloxstrap on Windows 10 and 11."
canonical: https://bloxstraplabs.ink/words/fastflags-fflags
updated: 2026-10-17
---

# FastFlags (FFlag, DFInt, FString, FLog)

Engine configuration variables read by RobloxPlayerBeta.exe from ClientAppSettings.json at startup.

## Facts (2026-10-17)

- **Term:** FastFlags (FFlag, DFInt, FString, FLog)
- **Summary:** Engine configuration variables read by RobloxPlayerBeta.exe from ClientAppSettings.json at startup.
- **Scope:** Bloxstrap & Roblox Windows Client

## What FastFlags (FFlag, DFInt, FString, FLog) means in Bloxstrap

Engine configuration variables read by RobloxPlayerBeta.exe from ClientAppSettings.json at startup.

Prefixes denote type and behavior: `FFlag` (boolean true/false), `FInt` (integer), `FString` (string), `FLog` (logging channel), and `D` prefix (`DFInt`, `DFFlag`) for dynamic flags that Roblox engineers can toggle.

## Where you encounter this in the app

Bloxstrap wraps low-level Roblox configuration files, log watchers, and registry handlers into a clean WPF settings menu so you rarely need to edit raw files by hand.

Download the latest Windows installer at [/download](https://bloxstraplabs.ink/download) or browse the [Engine](https://bloxstraplabs.ink/engine) and [Setup](https://bloxstraplabs.ink/setup) hubs for step-by-step guides.

## FAQ

### What is FastFlags (FFlag, DFInt, FString, FLog)?

Engine configuration variables read by RobloxPlayerBeta.exe from ClientAppSettings.json at startup. Prefixes denote type and behavior: `FFlag` (boolean true/false), `FInt` (integer), `FString` (string), `FLog` (logging channel), and `D` prefix (`DFInt`, `DFFlag`) for dynamic flags that Roblox engineers can toggle.

### Does this modify the Roblox game executable?

No. Bloxstrap only interacts with official configuration files, asset directories, and log files on disk.

## Related

- [Bloxstrap Technical Glossary](https://bloxstraplabs.ink/words)
- [Bloxstrap Engine & FastFlags](https://bloxstraplabs.ink/engine)
- [Bloxstrap Windows Setup & Installation](https://bloxstraplabs.ink/setup)
- [Can You Get Banned for Using Bloxstrap on Roblox?](https://bloxstraplabs.ink/ask/is-bloxstrap-safe-and-bannable-on-roblox)
- [ClientAppSettings.json](https://bloxstraplabs.ink/words/clientappsettings-json)

## Download

Free Windows app: [Download Bloxstrap](https://bloxstraplabs.ink/download)

Markdown mirror: https://bloxstraplabs.ink/words/fastflags-fflags.md