Pure Mode in FiveM: Server-Side File Integrity Enforcement

Running a FiveM server means balancing two competing interests: giving players the freedom to customize their experience and maintaining a fair, stable environment for everyone. Pure Mode is one of the most important tools server owners have for striking that balance. By validating client-side game files before a player fully connects, Pure Mode prevents modified assets from entering your server — whether those modifications are innocent visual tweaks or deliberate exploits.

Understanding how Pure Mode works, what each level actually blocks, and when to use which setting can save you hours of troubleshooting and prevent countless player complaints. This guide covers everything you need to know.

What Is Pure Mode?

Pure Mode is a built-in FiveM feature controlled by the sv_pureLevel convar in your server.cfg. When enabled, the server checks the hash values of specific client-side files during the connection handshake. If a player's files don't match the expected vanilla versions, the server rejects the connection with a "Files have been modified" error.

This is not a full anti-cheat system. Pure Mode only inspects files that are loaded at startup — it cannot detect runtime memory injections, external overlays, or cheat software that operates outside the game's file structure. Think of it as a first line of defense, not a complete security solution.

Technical Implementation

Pure Mode is configured through a single line in your server configuration:

# 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

Level 0 — Disabled (Default)

With sv_pureLevel 0, no file validation is performed. Players can join with any combination of modified files, including custom textures, replacement models, audio packs, ENB/ReShade presets, and even modified script files. This is the default setting on every FiveM server.

Best for: Development servers, servers that actively encourage client-side modding, or communities where visual customization is part of the culture.

Level 1 — Light Mode

Level 1 takes a selective approach. It permits modifications to files that are primarily cosmetic while blocking file types that can alter gameplay logic:

Allowed:

• .ytd texture files (custom skins, vehicle liveries, UI textures)
• .ydd and .ydr model variations (clothing, vehicle body kits)
• Audio modifications (custom radio stations, engine sounds)

Blocked:

• .ysc script files (game logic modifications)
• .asi injectors (common cheat delivery method)
• Modified executables and DLLs

This level is popular because it lets players keep their visual mods — custom car textures, clothing packs, or even graphical presets that rely on texture replacements — while preventing the file types most commonly associated with cheating.

Best for: Roleplay servers, casual communities, and any server where player self-expression matters but you still want baseline protection against script-based exploits.

Level 2 — Harsh Mode

Level 2 blocks all file modifications that aren't explicitly whitelisted by FiveM itself. This includes graphical enhancement mods, custom radio stations, texture replacements, and model swaps. Only completely vanilla game files pass validation.

Best for: Competitive servers, racing communities, servers with prize pools, or any environment where absolute fairness is more important than visual customization.

How the Connection Process Works

When a player connects to a server running Pure Mode, the following sequence occurs:

1. The client initiates a connection and begins the handshake.
2. The server requests hash values for specific game files based on the active sv_pureLevel.
3. The client computes and sends file hashes.
4. The server compares received hashes against known vanilla values.
5. If all hashes match, the connection proceeds normally.
6. If mismatches are detected, the player receives a "Files have been modified" error and is disconnected.

Players who are rejected must restart FiveM entirely — the client needs a full restart to reload vanilla files from its cache. Simply disconnecting and reconnecting will not work because the modified files remain in memory.

How Pure Mode Affects Player Experience

The impact on players depends heavily on which level you choose.

On Level 1 servers, most players won't notice anything different. The majority of popular FiveM visual mods — car texture packs, custom clothing, and audio replacements — use the file types that Level 1 permits. Players who use script-based mods or .asi loaders will be blocked, but that's generally the intended outcome.

On Level 2 servers, the experience is more restrictive. Players who are accustomed to running ENB presets, ReShade configurations, or any visual modifications will be unable to join without removing them first. This can cause friction, especially in communities that previously allowed visual mods. Clear communication about your Pure Mode policy — ideally in your server listing, Discord, and connection screen — helps reduce support tickets.

Connection time increases slightly with Pure Mode enabled. The hash validation process adds roughly 2-5 seconds to the initial connection. After that, there is no ongoing performance impact during gameplay.

Pure Mode and Other Security Measures

Pure Mode works best as part of a layered security approach. On its own, it handles file integrity but leaves gaps that other tools need to fill:

• Anti-cheat resources like those covered in our best FiveM anticheat scripts guide detect runtime cheats, injection attacks, and suspicious player behavior that Pure Mode cannot see.
• Server-side validation ensures that critical game logic (damage calculations, inventory limits, economy transactions) is authoritative on the server rather than trusting client-reported values.
• Admin tools and logging provide the human oversight layer, letting staff investigate reports and review player activity.

A solid security setup for a competitive server might look like this:

sv_pureLevel 2
# Combine with anti-cheat resource

ensure your-anticheat-resource
ensure admin-logging-system

For roleplay servers that want a less restrictive but still protected environment:

sv_pureLevel 1
# Allow visual customization while blocking exploits

Choosing the Right Level for Your Server

The right Pure Mode level depends on your server's purpose and community expectations.

Server Type	Recommended Level	Reasoning
Development/Testing	0	No restrictions needed during development
Casual RP	0 or 1	Allow personal expression, block obvious exploits
Serious RP	1	Visual mods enhance immersion, script mods don't belong
Competitive/Racing	2	Absolute fairness required, no visual advantages
Prize Pool Events	2	Legal and fairness requirements demand strict enforcement

If you run a serious roleplay community, Level 1 is usually the sweet spot. It allows players to use custom clothing packs and vehicle textures that enhance their characters while blocking the file types that enable cheating. For servers optimizing their FiveM settings for performance, Level 1 also avoids the player friction that Level 2 can create.

Limitations and Considerations

False Positives: Some legitimate accessibility modifications (colorblind filters, UI scaling tools) may be blocked at Level 2. Server owners currently cannot create custom whitelists for specific file modifications — it's an all-or-nothing setting at each level.

Determined Cheaters: Pure Mode does not stop players who use memory-based cheats, external overlays, or tools that operate outside the game's file system. It is a deterrent against casual file modification, not a barrier against sophisticated cheating.

Player Communication: Switching from Level 0 to Level 1 or 2 will inevitably cause confusion. Announce the change in advance, explain why you're making it, and provide clear instructions for players who need to remove their mods.

FAQ

Can I switch Pure Mode levels without restarting the server? No. Changes to sv_pureLevel require a full server restart to take effect.

Will Pure Mode block FiveM resource files streamed by the server? No. Server-streamed resources (assets sent via stream folders in your resources) are handled separately from client-side file validation. Pure Mode only checks files that exist on the player's local machine.

Do players need to reinstall GTA V to pass Pure Mode checks? Usually not. Restarting FiveM is enough in most cases, as the client reloads vanilla files from its cache. If a player has directly modified GTA V's installation files (rather than using a mod loader), they may need to verify their game files through Steam or the Rockstar Launcher.

Does Pure Mode affect server performance? The validation happens only during the connection handshake. There is no measurable impact on server performance during normal gameplay.

Summary: Pure Mode provides baseline file integrity verification for FiveM servers but requires supplementary anti-cheat measures for comprehensive protection against cheating. Choose Level 1 for a balanced approach or Level 2 when strict fairness is non-negotiable.