Startup Flags - ComfyUI

ComfyUI accepts command-line arguments when started with python main.py. This page documents every flag defined in comfy/cli_args.py.

Windows Portable users can add flags to the .bat launch files (for example, run_nvidia_gpu.bat). See the Windows Portable guide for details.

Run python main.py --help in your ComfyUI directory for the built-in help text. Combine multiple flags as needed:

python main.py --listen 0.0.0.0 --port 8288 --disable-auto-launch --lowvram

Network & Server

Flag	Default	Description
`--listen` `[IP]`	`127.0.0.1`	IP address to listen on. Comma-separated list supported (e.g. `127.2.2.2,127.3.3.3`). If provided without a value, defaults to `0.0.0.0,::` (all IPv4 and IPv6 interfaces).
`--port`	`8188`	Port to listen on.
`--tls-keyfile` `PATH`	—	Path to TLS (SSL) key file. Enables HTTPS. Requires `--tls-certfile`.
`--tls-certfile` `PATH`	—	Path to TLS (SSL) certificate file. Enables HTTPS. Requires `--tls-keyfile`.
`--enable-cors-header` `[ORIGIN]`	disabled	Enable CORS. Optional origin, or `*` for all origins when no value is given.
`--max-upload-size`	`100`	Maximum upload size in MB.
`--enable-compress-response-body`	disabled	Enable compressing the HTTP response body.

# Listen on all interfaces (LAN access)
python main.py --listen

# Listen on a specific IP
python main.py --listen 0.0.0.0

# Custom port with HTTPS
python main.py --port 8443 --tls-keyfile key.pem --tls-certfile cert.pem

Directories

Flag	Default	Description
`--base-directory` `PATH`	ComfyUI root	Base directory for models, custom_nodes, input, output, temp, and user directories.
`--extra-model-paths-config` `PATH`	—	Load one or more `extra_model_paths.yaml` files. Can be specified multiple times.
`--output-directory` `PATH`	—	Output directory. Overrides `--base-directory`.
`--temp-directory` `PATH`	—	Temp directory. Overrides `--base-directory`.
`--input-directory` `PATH`	—	Input directory. Overrides `--base-directory`.
`--user-directory` `PATH`	—	User directory (absolute path). Overrides `--base-directory`. Path must exist and be readable.

Launch & Browser

Flag	Default	Description
`--auto-launch`	disabled	Automatically open ComfyUI in the default browser on startup.
`--disable-auto-launch`	disabled	Disable auto-launching the browser.
`--windows-standalone-build`	disabled	Windows portable build convenience mode. Enables auto-launch on startup (equivalent to `--auto-launch`).

--windows-standalone-build sets auto_launch to true. --disable-auto-launch overrides it. To run as a server without opening a browser, use --disable-auto-launch.

# Run server without opening browser
python main.py --disable-auto-launch

Devices & CUDA

Flag	Default	Description
`--cuda-device` `DEVICE_ID`	—	CUDA device IDs to use, comma-separated (e.g. `0` or `0,1`). Other devices are hidden.
`--default-device` `ID`	—	Default device ID. All other devices remain visible.
`--cuda-malloc`	auto (torch 2.0+)	Enable cudaMallocAsync. Mutually exclusive with `--disable-cuda-malloc`.
`--disable-cuda-malloc`	—	Disable cudaMallocAsync. Mutually exclusive with `--cuda-malloc`.
`--directml` `[DEVICE]`	—	Use torch-directml. Optional device index; defaults to `-1` when no value is given.
`--oneapi-device-selector` `STRING`	—	oneAPI device selector string for Intel devices.

Precision & Inference

Flags in the Global, UNET, VAE, and Text Encoder groups below are mutually exclusive within each group. Only one flag per group can be used at a time.

Global floating point

Flag	Description
`--force-fp32`	Force fp32 globally. Report if this improves GPU performance.
`--force-fp16`	Force fp16 globally. Also sets `--fp16-unet`.

UNET precision

Flag	Description
`--fp32-unet`	Run the diffusion model in fp32.
`--fp64-unet`	Run the diffusion model in fp64.
`--bf16-unet`	Run the diffusion model in bf16.
`--fp16-unet`	Run the diffusion model in fp16.
`--fp8_e4m3fn-unet`	Store UNet weights in fp8 (e4m3fn).
`--fp8_e5m2-unet`	Store UNet weights in fp8 (e5m2).
`--fp8_e8m0fnu-unet`	Store UNet weights in fp8 (e8m0fnu).

VAE precision

Flag	Description
`--fp16-vae`	Run the VAE in fp16. May cause black images.
`--fp32-vae`	Run the VAE in full precision fp32.
`--bf16-vae`	Run the VAE in bf16.
`--cpu-vae`	Run the VAE on the CPU (not mutually exclusive with VAE precision flags).

Text encoder precision

Flag	Description
`--fp8_e4m3fn-text-enc`	Store text encoder weights in fp8 (e4m3fn).
`--fp8_e5m2-text-enc`	Store text encoder weights in fp8 (e5m2).
`--fp16-text-enc`	Store text encoder weights in fp16.
`--fp32-text-enc`	Store text encoder weights in fp32.
`--bf16-text-enc`	Store text encoder weights in bf16.

Other inference options

Flag	Default	Description
`--fp16-intermediates`	disabled	Experimental: use fp16 for intermediate tensors between nodes instead of fp32.
`--force-channels-last`	disabled	Force channels-last memory format during inference.
`--supports-fp8-compute`	disabled	Act as if the device supports fp8 compute.
`--enable-triton-backend`	disabled	Enable Triton backend in comfy-kitchen. Disabled by default at launch.

Preview

Flag	Default	Description
`--preview-method`	`none`	Preview method for sampler nodes. Choices: `none`, `auto`, `latent2rgb`, `taesd`.
`--preview-size`	`512`	Maximum preview image size in pixels.

Cache

Cache mode flags are mutually exclusive. Only one of --cache-ram, --cache-classic, --cache-lru, or --cache-none should be used.

Flag	Default	Description
`--cache-ram` `[GB] [GB]`	enabled (default mode)	RAM pressure caching. First value: active-cache threshold in GB. Optional second value: inactive-cache/pin threshold in GB. When no values given: active = 10% of system RAM (min 2 GB, max 10 GB); inactive = 100% of system RAM (max 96 GB). Accepts at most two values.
`--cache-classic`	—	Use the old aggressive caching style.
`--cache-lru` `N`	`0` (disabled)	LRU caching with a maximum of N node results cached. May use more RAM/VRAM.
`--cache-none`	—	Reduced RAM/VRAM usage; re-executes every node on each run.

Attention

Cross-attention method flags are mutually exclusive. Split and quad attention are ignored when xformers is used.

Flag	Description
`--use-split-cross-attention`	Use split cross attention optimization.
`--use-quad-cross-attention`	Use sub-quadratic cross attention optimization.
`--use-pytorch-cross-attention`	Use PyTorch 2.0 cross attention.
`--use-sage-attention`	Use Sage attention.
`--use-flash-attention`	Use FlashAttention.
`--disable-xformers`	Disable xformers.
`--force-upcast-attention`	Force attention upcasting. Report if this fixes black images. Mutually exclusive with `--dont-upcast-attention`.
`--dont-upcast-attention`	Disable all attention upcasting. For debugging only.

VRAM & Memory

VRAM mode flags (--gpu-only, --highvram, --lowvram, --novram, --cpu) are mutually exclusive.

Flag	Default	Description
`--gpu-only`	—	Store and run everything on the GPU (text encoders, CLIP, etc.).
`--highvram`	—	Keep models in GPU memory instead of unloading to CPU after use.
`--lowvram`	—	No effect when dynamic VRAM is enabled. Otherwise, runs text encoders on CPU.
`--novram`	—	Minimal VRAM usage when `--lowvram` is not enough.
`--cpu`	—	Use CPU for everything (slow).
`--reserve-vram` `GB`	OS-dependent	VRAM in GB to reserve for the OS and other software.
`--async-offload` `[NUM_STREAMS]`	enabled on Nvidia	Async weight offloading. Optional stream count (default: 2).
`--disable-async-offload`	—	Disable async weight offloading.
`--disable-dynamic-vram`	—	Disable dynamic VRAM; use estimate-based model loading.
`--enable-dynamic-vram`	auto on Nvidia	Enable dynamic VRAM on systems where it is not enabled by default.
`--fast-disk`	disabled	Prefer disk-backed dynamic loading over unpinned RAM. Useful with fast NVMe.
`--force-non-blocking`	disabled	Force non-blocking tensor operations. May help on non-Nvidia systems; can break some workflows.
`--disable-smart-memory`	disabled	Aggressively offload to RAM instead of keeping models in VRAM.
`--disable-pinned-memory`	disabled	Disable pinned memory use.
`--mmap-torch-files`	disabled	Use mmap when loading ckpt/pt files.
`--disable-mmap`	disabled	Do not use mmap when loading safetensors.

Performance & Debugging

Flag	Default	Description
`--fast` `[OPT...]`	disabled	Enable experimental optimizations that may affect quality or stability. `--fast` alone enables all. Specific options: `fp16_accumulation`, `fp8_matrix_mult`, `cublas_ops`, `autotune`.
`--deterministic`	disabled	Use slower deterministic PyTorch algorithms where possible. Does not guarantee identical images in all cases.
`--default-hashing-function`	`sha256`	Hash function for duplicate filename/content comparison. Choices: `md5`, `sha1`, `sha256`, `sha512`.

# Enable all fast optimizations (experimental)
python main.py --fast

# Enable specific optimizations only
python main.py --fast fp16_accumulation cublas_ops

ComfyUI Manager

See ComfyUI-Manager Installation for setup instructions.

Flag	Description
`--enable-manager`	Enable ComfyUI-Manager.
`--disable-manager-ui`	Disable Manager UI and endpoints only. Background tasks (scheduled installs, etc.) continue. Requires `--enable-manager`.
`--enable-manager-legacy-ui`	Use the legacy Manager UI. Requires `--enable-manager`.

Custom Nodes & API Nodes

Flag	Default	Description
`--disable-all-custom-nodes`	disabled	Disable loading all custom nodes.
`--whitelist-custom-nodes` `FOLDER...`	—	Custom node folders to load even when `--disable-all-custom-nodes` is set.
`--disable-api-nodes`	disabled	Disable API nodes and prevent the frontend from communicating with the internet.
`--disable-metadata`	disabled	Disable saving prompt metadata in output files.

# Troubleshoot custom node issues
python main.py --disable-all-custom-nodes

# Allow only specific custom nodes
python main.py --disable-all-custom-nodes --whitelist-custom-nodes ComfyUI-Manager

Frontend & API

Flag	Default	Description
`--front-end-version`	`comfyanonymous/ComfyUI@latest`	Frontend version in `[owner]/[repo]@[version]` format. Requires internet to download from GitHub releases. Version can be `latest` or a semver (e.g. `1.0.0`).
`--front-end-root` `PATH`	—	Local filesystem path to the frontend directory. Overrides `--front-end-version`.
`--comfy-api-base`	`https://api.comfy.org`	Base URL for the ComfyUI API.
`--database-url`	`sqlite:///<ComfyUI>/user/comfyui.db`	Database URL. Use `sqlite:///:memory:` for in-memory.
`--enable-assets`	disabled	Enable the assets system (API routes, database sync, background scanning).
`--feature-flag` `KEY[=VALUE]`	—	Set a server feature flag. Bare `KEY` sets true. Can be repeated. Booleans and numbers are auto-converted.
`--list-feature-flags`	—	Print known CLI-settable feature flags as JSON and exit.

# List available feature flags
python main.py --list-feature-flags

# Set feature flags
python main.py --feature-flag show_signin_button=true

Logging & Misc

Flag	Default	Description
`--verbose` `[LEVEL]`	`INFO`	Logging level. Choices: `DEBUG`, `INFO`, `WARNING`, `ERROR`, `CRITICAL`. `--verbose` alone sets `DEBUG`.
`--log-stdout`	disabled	Send normal process output to stdout instead of stderr.
`--dont-print-server`	disabled	Do not print server output to the console.
`--multi-user`	disabled	Enable per-user storage.
`--quick-test-for-ci`	disabled	Quick startup test for CI. Exits immediately after initialization.

This reference is based on ComfyUI comfy/cli_args.py. When upgrading ComfyUI, run python main.py --help or compare your local cli_args.py against this page to check for new or changed flags.

​Network & Server

​Directories

​Launch & Browser

​Devices & CUDA

​Precision & Inference

​Global floating point

​UNET precision

​VAE precision

​Text encoder precision

​Other inference options

​Preview

​Cache

​Attention

​VRAM & Memory

​Performance & Debugging

​ComfyUI Manager

​Custom Nodes & API Nodes

​Frontend & API

​Logging & Misc

Network & Server

Directories

Launch & Browser

Devices & CUDA

Precision & Inference

Global floating point

UNET precision

VAE precision

Text encoder precision

Other inference options

Preview

Cache

Attention

VRAM & Memory

Performance & Debugging

ComfyUI Manager

Custom Nodes & API Nodes

Frontend & API

Logging & Misc