Viewfinder

A shader debugging mod for Iris on Fabric that exposes an HTTP API and in-game commands for external tools and scripts to inspect, test, and automate shader development workflows.

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fabricutility

Rent Server with this Mod

About this Mod

Viewfinder

A shader debugging mod for Iris on Fabric that exposes an HTTP API and in-game commands for external tools and scripts to inspect, test, and automate shader development workflows.

Features

Shader reload and error list - trigger shader reloads and capture compilation errors
GPU timing metrics - collect per-pass GPU timing data (collects multiple frames to average out noise)
Texture dumping - export textures as PNG or raw binary by name (colortex0, or custom texture)
SSBO buffer dumping - dump shader storage buffer objects to disk for analysis
Screenshot scheduling - schedule screenshots with configurable frame delay (for PT)
Patched shader listing - find which patched shader errored programmatically by listing all and searching for "errored"

Installation

Install Fabric Loader (≥ 0.18.4) for Minecraft 26.1
Install Fabric API and Iris (which requires Sodium)
Drop the Viewfinder .jar into your mods/ folder

Usage

In-game commands

All commands are registered under /viewfinder:

Command	Description
`/viewfinder status`	Show current shaderpack name, error count, and API address
`/viewfinder reload`	Reload shaders and report any compilation errors
`/viewfinder errors`	List all captured shader errors
`/viewfinder screenshot [frames]`	Take a screenshot (optionally delayed by N frames)
`/viewfinder screenshot result`	Show the path of the last screenshot
`/viewfinder metrics`	Display per-pass GPU timings
`/viewfinder ssbo list`	List active SSBO buffers
`/viewfinder ssbo dump <index>`	Dump an SSBO buffer to `ssbo_dumps/`
`/viewfinder texture list`	List available colortex and custom textures
`/viewfinder texture dump name <name> [raw]`	Dump a texture by name (PNG or raw)
`/viewfinder texture dump id <id> [raw]`	Dump a texture by GL id (PNG or raw)
`/viewfinder patched_shaders`	List Iris patched shader files

HTTP API

Viewfinder starts an HTTP server on localhost:7150. A full OpenAPI 3.0 spec is available at GET /.

Method	Endpoint	Description
`GET`	`/`	OpenAPI 3.0 specification
`GET`	`/status`	Shaderpack status (loaded pack name)
`POST`	`/reload`	Reload shaders, returns success and errors
`GET`	`/errors`	List captured shader errors
`POST`	`/screenshot?frames=N`	Schedule a screenshot (default: next frame)
`GET`	`/screenshot/result`	Path to the last saved screenshot
`GET`	`/metrics`	GPU timing metrics
`GET`	`/list-ssbo`	List active SSBO buffers
`POST`	`/ssbo?index=N`	Dump SSBO at given index
`GET`	`/list-textures`	List available textures
`POST`	`/texture?name=...&raw=bool`	Dump texture by name
`POST`	`/texture?id=...&raw=bool`	Dump texture by GL id
`GET`	`/patched_shaders`	List patched shader files

All responses are JSON. Dumped files (textures, SSBOs, screenshots) are written to subdirectories inside the Minecraft game directory.

Available Versions

1.0.0release

MC 26.1fabric

March 26, 2026

How to Install Viewfinder on Your Server

Order Server

Order a Minecraft Java server with at least 3 GB RAM (4 GB recommended).

Set fabric Loader

In the panel under "Egg", select the fabric loader and matching Minecraft version (26.1).

Install Mod

Open the mod browser in the dashboard and search for "Viewfinder". Click "Install" – done! Alternatively, upload the .jar via SFTP to the /mods folder.

Compatibility

Mod Loaders

fabric

Minecraft Versions

26.1

Server-side

✗ Unsupported

Recommended RAM

4 GB(min. 3 GB)

Frequently Asked Questions

Viewfinder server crashes on startup – what to do?

Most common cause: wrong fabric version or insufficient RAM. Check the server log (latest.log) for "OutOfMemoryError" or "Mixin" errors. With Mado Hosting: ensure at least 3 GB RAM is allocated and the loader matches the mod version (26.1). You can switch loaders with one click in the panel.

Is Viewfinder compatible with fabric?

Viewfinder officially supports fabric for Minecraft 26.1. The Mado dashboard automatically detects incompatible loader combinations.

Server lagging with Viewfinder – how to optimize performance?

Recommended RAM: 4 GB (per 8 players). Use /spark profiler to check if Viewfinder consumes the most tick time. Common fixes: reduce server view-distance to 8-10, install "performant" or "starlight" as supplementary mods on Forge. With Mado Hosting, your server runs on NVMe SSDs with dedicated CPU cores for minimal latency.