S1API (Forked)
🟡 Updated this yearPreview
🔍 Analysis
- 👍 0.6% endorsement rate
- 🏆 #3 of 159 Utilities mods in this game by downloads
📋 About This Mod
S1API — Schedule One Modding API (Community Continued Fork)
A cross-compatibility layer for Schedule One (Mono & IL2CPP)
Originally created by KaBooMa, S1API standardizes common modding tasks for Schedule One.
This maintained fork — GitHub: ifBars/S1API — delivers fixes and updates while preserving the original goals.
If you use any S1API mods that add custom NPCs, be aware that their mugshots are generated at runtime (after loading a save).
When those mugshots are captured by the Unity camera, the screen can briefly jump to a very bright "Unity lighting" frame for each new NPC.
Players sensitive to flashing lights or with photosensitivity/epilepsy concerns should proceed with caution.
The brief flash frame lasts ~1-2 seconds for each custom NPC.
What S1API Does
A shared foundation so mod creators can focus on content — not re-discovering game internals. Common functionality is unified behind a stable API with Mono/IL2CPP coverage and automatic game-branch detection.
Who Needs This?
• Players using mods that declare S1API as a requirement.
• Mod authors who want a consistent, community-maintained API layer.
Note: The original S1API is outdated for current game versions; use this fork for compatibility.
Features at a Glance
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[]Cross-version support for Schedule One (Mono & IL2CPP).[/]
[]Automatic detection of main vs. alternate game branches.[/]
[]Centralized helpers/utilities to reduce boilerplate in mods.[/]
[]Best and only API for things like custom phone apps, NPCs, and more[/]
[]Open documentation and example mods for fast onboarding.[/]
[]Actively maintained: fixes and improvements shipped via GitHub releases.[/]
Installation
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[]Download the latest release of this fork.[/]
[]Extract the archive.[/]
[]Copy the Plugins and Mods folders into your Schedule One directory (typically steamapps/common/Schedule I/).[/]
[]Launch the game — S1API will auto-detect your branch (main or alternate).[/]
Uninstall: Remove the S1API files you added from Plugins and Mods.
For Mod Authors
• Read the Documentation Site for
-
[]Download the latest release of this fork.[/]
S1API is an open-source framework that standardizes Schedule One modding by providing common functionalities, so modders can focus on content creation instead of reverse engineering. With 765 endorsements and frequent updates, it's a community-backed utility for Schedule One mod developers.
✨ Key Features
📊 Pros & Cons
✅ Pros
- Community-approved with 765 endorsements and 143k downloads
- Actively maintained (last updated August 2026)
- Solves a real pain point: no more digging through game code for basics
⚠️ Cons
- Not a content mod—it's a framework, so players won't see direct changes
- Requires other mods to be built on it to be useful
- Potential compatibility risk if other mods don't use this API
For Schedule One mod developers who want a shared foundation to build on. If you're a player looking for gameplay tweaks, this isn't for you. Skip if you prefer standalone mods that don't rely on external APIs.
💡 Beginner Tips
- Install this mod first so other mods that depend on it can find it
- Check the mod's documentation for how to integrate it into your own mods
- Since it's a utility, you won't see it in-game—it works behind the scenes
📊 Mod Details
- Game
- Schedule1 Mods
- Author
- S1API Contributors
- Version
- 3.2.0
- Downloads
- 143,091
- Endorsements
- 792
- Category
- Utilities
- Created
- 9/11/2025
- Updated
- 8/16/2026
🧩 Commonly Used Together
Users add these mods to the same collections — a real compatibility signal, not an AI guess.
🔧 How to Install Schedule I Mods
Download from Nexus Mods.
📖 Full step-by-step install guide for Schedule I →
Visit the official mod page for specific installation instructions for this mod.
🎮 Need cheat codes or console commands? Check ur gaming wiki for Schedule I commands, item IDs, and more.
Keep browsing — more Schedule I mods await