
Pure Mode in FiveM: Server-Side File Integrity Enforcement
June 7, 2025
Last Updated: February 26, 2026
2 min read
Pure Mode is a server configuration feature in FiveM that validates client game files against a predefined list, preventing players from joining with modified files that could provide unfair advantages or destabilize gameplay.
Technical Implementation
Pure Mode operates through the sv_pureLevel server convar:
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# In server.cfg
sv_pureLevel 0 # Disabled (default)
sv_pureLevel 1 # Light Mode - Allows some visual/audio mods
sv_pureLevel 2 # Harsh Mode - Blocks all client modifications
Mode Differences
Level 0 (Disabled)
- No file validation performed
- All client modifications allowed
Level 1 (Light)
- Permits:
.ytdtexture files,.ydd/.ydrmodel variations, audio modifications - Blocks:
.yscscripts,.asiinjectors, modified executables
Level 2 (Harsh)
- Blocks all file modifications except those explicitly whitelisted by FiveM
- Includes graphical enhancement mods and custom radio stations
Client Connection Process
- Player attempts connection with modified files
- Server performs file hash validation
- If mismatches detected: “Files have been modified” error appears
- Player must restart FiveM to load vanilla files
Limitations and Considerations
Not a Complete Anti-Cheat Solution
- Only validates files loaded at startup
- Cannot detect memory modifications or external cheats
- Should be combined with dedicated anti-cheat resources
Performance Impact
- Initial connection may take 2-5 seconds longer for validation
- No runtime performance impact after connection
False Positives
- Some legitimate accessibility mods (colorblind filters, UI scaling) may be blocked
- Server owners cannot whitelist specific modifications
Recommended Implementation
For competitive servers:
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sv_pureLevel 2
# Combine with anti-cheat resource
ensure your-anticheat-resource
For roleplay/casual servers:
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sv_pureLevel 1
# Allow visual customization while blocking exploits
Summary: Pure Mode provides baseline file integrity verification for FiveM servers but requires supplementary anti-cheat measures for comprehensive protection against cheating.
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