the phone-home register

llama.cpp

What llama.cpp sends out of your computer by default, when, to whom, and the switch that stops it, version by version, with how we know.

The answer

By its build files at commit 3cf03257 and its source at b11312, not run: a CMake build of llama.cpp by default downloads a prebuilt web UI from huggingface.co when no UI files are on disk (with your Hugging Face token as a header if HF_TOKEN is set), and -DLLAMA_USE_PREBUILT_UI=OFF stops it; the server's web UI, on by default, asks huggingface.co and llama.app from your browser when you use its model browser (whether opening the UI alone asks was not read), and --no-webui stops that; a keyword search of the server itself found no telemetry name, and its own calls were not enumerated.

Builds and versions

not installed: source read at b11312On by default?not read · a keyword search found nothing in the server; unclear · read in codeMeasured here?no · read in codeDate checked (UTC)2026-10-01 to 2026-10-10

Version: b11312 · the source at b11312 (commit 0c1e5709)
Where the evidence came from: not run: the source applies to every platform it builds
On by default?: not read · a keyword search found nothing in the server; unclear · read in code: the web UI's model browser asks Hugging Face and llama.app from your browser; whether opening the UI alone asks was not read
Measured here?: no · read in code
Date checked (UTC): 2026-10-01 to 2026-10-10
Why we say so: the server's source searched by name for telemetry at b11312; its own network calls were not enumerated; the web UI's Hub service and its constants read at b11312; pull requests #27947 and #27959 (merged 2026-09-30) added them

not installed: the build files read at commit 3cf03257On by default?yes · read in codeMeasured here?no · read in codeDate checked (UTC)2026-10-10

Version: 3cf03257 · a CMake build from source at commit 3cf03257
Where the evidence came from: not run: the build files apply to every CMake build
On by default?: yes · read in code: during the build, its default option downloads the web UI
Measured here?: no · read in code
Date checked (UTC): 2026-10-10
Why we say so: tools/ui/CMakeLists.txt and scripts/ui-assets.cmake read at 3cf03257 (the provisioning step, its order of preference, its requests and its token header), with the option in CMakeLists.txt

Each call out

Not read · b11312

Version · build: b11312 · the source at b11312 (commit 0c1e5709) · not run: the source applies to every platform it builds · not installed: source read at b11312
Sends by default: not read · a keyword search found nothing in the server
Also know: Downloads by name (-hf) reach Hugging Face by design; --offline (LLAMA_ARG_OFFLINE) forces the cache and prevents network access. — github.com · arg.cpp, read 2026-10-10
The browser arm that would load the web UI and count what it asks for has not run. — its row: llama-cpp-b11312-source/webui-model-browser, read 2026-10-10
Grade and method: read · the server's source searched by name for telemetry at b11312; its own network calls were not enumerated · read 2026-10-01
Receipts: --offline: 'forces use of cache, prevents network access' · the server README's flag table · the --host flag's default

webui model browser · b11312

Version · build: b11312 · the source at b11312 (commit 0c1e5709) · not run: the web UI runs in your browser · not installed: source read at b11312
Sends by default: unclear · read in code: the web UI's model browser asks Hugging Face and llama.app from your browser; whether opening the UI alone asks was not read
Kind: fetches
Trigger: only when you ask for it
When: Your browser, from the tool's web UI: the code at b11312 fetches a model catalogue and Hugging Face model data when its model browser asks; downloads then run through the server. Not run.
Where: model hub · huggingface.co; llama.app
What it sends: model searches, file lists and model details (request); a request for a model catalogue (request)
The vendor's stated purpose: “Adds a stateless Hugging Face Hub data layer: `HuggingFaceService` (GGUF repo search, file tree, model details), its constants/enums/types in `$lib`, GGUF filename analysis (quant + sidecar metadata, shard-set collapsing, size/param parsing) and an `orgOf()` helper on the model name utils.” — pull request #27947 (merged 2026-09-30), read 2026-10-10
Grade and method: read · the web UI's Hub service and its constants read at b11312; pull requests #27947 and #27959 (merged 2026-09-30) added them · read 2026-10-10
not exercised: loading the web UI in a browser (the browser arm is owed)
Receipts: the catalogue address · the Hugging Face address · the catalogue fetch · the web UI's default and its flag · pull request #27947 a house page; the receipts are above

prebuilt ui download · 3cf03257

Version · build: 3cf03257 · a CMake build from source at commit 3cf03257 · not run: the build files apply to every CMake build · not installed: the build files read at commit 3cf03257
Sends by default: yes · read in code: during the build, its default option downloads the web UI
Kind: fetches
Trigger: as a side effect of a local request
When: During the build, when no web UI files were built or placed locally: the default CMake option downloads a prebuilt web UI from a Hugging Face bucket, the checksum file first and then the archive, skipping the archive when a copy already on disk matches the checksum; a later build of the same version whose stamp matches skips the request.
Where: model hub · huggingface.co
What it sends: a request for the web UI archive's checksum file, then for the archive, for the build's version and, failing that, for 'latest' (request); your Hugging Face token, as an Authorization header, when HF_TOKEN is set in the build's environment (credential)
The vendor's stated purpose: “llama: use prebuilt UI from HF Bucket when available” — the option's own description in CMakeLists.txt (quoted whole), read 2026-10-10
Also know: A binary built this way then depends on what the bucket contained that day. — github.com · CMakeLists.txt, read 2026-10-10
Grade and method: read · tools/ui/CMakeLists.txt and scripts/ui-assets.cmake read at 3cf03257 (the provisioning step, its order of preference, its requests and its token header), with the option in CMakeLists.txt · read 2026-10-10
Receipts: the build option and its default · the provisioning step the build runs · the order of preference: local files, an npm build, then the bucket · the requests, the fallback to 'latest' and the token header · the archive's download, skipped when a copy on disk matches · the stamp that skips a repeat request · with no UI files, the build goes on without an embedded UI

The switch

--no-webui

Accepted values: set
What it is: command-line flag (env LLAMA_ARG_UI)
Where it must be set: on the server's command line · turn them off
Also turns off: the whole web UI
What turning it off costs: no web UI; the API still answers
Proof: documented; not tested by us
For the call: webui model browser · b11312

-DLLAMA_USE_PREBUILT_UI=OFF

Accepted values: set
What it is: CMake option
Where it must be set: on the cmake command line · turn them off
Also turns off: the prebuilt web UI: unless you place the UI files in tools/ui/dist or build them with -DLLAMA_BUILD_UI=ON (npm), the server is built without an embedded web UI
Proof: found in the build file; not tested by us
For the call: prebuilt ui download · 3cf03257

Listens beyond the machine, and other cloud features

Listens beyond the machine by default

loopback only · its server README at b11312: the --host flag binds the loopback address by default (tools/server/README.md, line 192) (b11312 the source at b11312 (commit 0c1e5709))
not covered here (b11312 the source at b11312 (commit 0c1e5709))
n/a · a build step (3cf03257 a CMake build from source at commit 3cf03257)

Other cloud features

None found.

What it leaves on disk

Nothing we know of.

Brings in, and installed for you by

None on the register.

Credit

None recorded.

Vendor documents it? · public discussion

Vendor documents it?

webui model browser · b11312: partly · The pull requests describe the model browser and its download pipeline; the server README names the web UI flag but not the browser's requests. · github.com · 27947 · github.com · 27959 · read 2026-10-10
prebuilt ui download · 3cf03257: partly · The option's description and the provisioning script's own comments describe the download and the token header; the project's README was not read for it. · github.com · CMakeLists.txt · github.com · ui-assets.cmake · github.com · ui-assets.cmake · read 2026-10-10