Spec Driven Development
by formulahendry
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
Runs on your computer★ 440MITUpdated 14 months ago
Install
Fanout
Overview
Description from the maker (original English)
Investigate OpenTelemetry traces, metrics, and logs, and manage personal dashboards.
PopNx MCP’s three pillars
These three are never merged into one score: opinions, measurements and popularity are different things.
- User voiceiNo reviews yetReviews open together with accounts in a later step
- Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
- UsageiNot measured yet★ –
What you can do with it
We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.
- Connection: Runs in the cloud
- Transport: Streamable HTTP
- Category: Other
Install
Pick the AI app you use, then copy the settings.
Before you install
- Basic checks: 1 of 1 passed
- Runs on the maker’s server: what you ask it goes through their server.
- The registry lists no key to fill in.
You need
- Runs in the cloudNothing to install; it connects over the internet
Which app do you use?
Pick your app above. We remember it, so next time the button says “Install in …”.
Works in Claude on the web, desktop and mobile:
- Open Settings → Connectors
- Press Add custom connector
- Paste the address below and press Add
- If it asks you to sign in, sign in with the maker
https://{fanout_host}/mcpThe address contains {…} parts that only you know (such as your account), so copy it and fill them in.
Run this in your terminal
claude mcp add --transport http fanout 'https://{fanout_host}/mcp'The address contains {…} parts that only you know (such as your account), so copy it and fill them in.
Or copy the settings yourself
Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json
{
"mcpServers": {
"fanout": {
"url": "https://{fanout_host}/mcp"
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
The address contains {…} parts that only you know (such as your account), so copy it and fill them in.
Or copy the settings yourself
Paste into .vscode/mcp.json in your project
{
"servers": {
"fanout": {
"type": "http",
"url": "https://{fanout_host}/mcp"
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
ChatGPT connects only to servers on the internet:
- Open ChatGPT on the web → Settings → Connectors (Apps)
- Press Create or Add (some plans need Developer mode under Advanced first)
- Paste the address below, give it a name and save
- If it asks you to sign in, sign in with the maker
https://{fanout_host}/mcpThe address contains {…} parts that only you know (such as your account), so copy it and fill them in.
Menu names can differ slightly by plan and over time.
Your choice stays on this device in a cookie; no account needed.
These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.
What it can do
The address needs your own values, so we cannot read the tool list for you.
Basic checksi
We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 6, 2026
- ✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account labstack, which owns the repo
- … Not checked yet
Still maintained
We have not read this repo from GitHub yet
- … Not checked yet
Has a licence
We have not read this repo from GitHub yet
- – Not applicable
Endpoint responds
The address needs your own account values, so we cannot check it for you
- – Not applicable
Sign-in with OAuth
The address needs your own account values, so we cannot check it for you
- … Not checked yet
No hidden instructions in tool descriptions
Not checked yet; we read the tool list when we check the endpoint
Compared with others in Otheri
- More stars than 0% of the other 32398 servers in this category
- Published to the registry more recently than 96% of the other 32398 servers in this category
- Basic checks equal to or better than 100% of the other 32398 servers in this category
Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.
Common questions
Is Fanout safe?
It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.
What keys or codes does it need?
The registry does not list a required key, though some servers ask you to sign in on first use.
Does it run on my computer or in the cloud?
It runs in the maker’s cloud. Connect over the internet with nothing to install, but what you send passes through the maker’s servers.
Is it still maintained?
The GitHub repo last changed –, and the latest version (2026.11.0-alpha) reached the registry yesterday.
Which apps can use it?
Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT in developer mode.
What can I use instead?
In the same category: Spec Driven Development, Remote Desktop Commander, AI Deprecations
Alternatives
Servers in the same category from other makers, sorted by stars.
Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi
Remote Desktop Commander
by desktop-commander
Remote Desktop Commander: use files, terminal and processes on your own computers from any AI app.
Runs in the cloud★ 211Updated yesterday
Install
AI Deprecations
by aideprecations.com
AI model shutdown dates, replacements, change feed and webhook alerts for 8 providers.
Runs in the cloudUpdated today
Install
README from the maker
Open the README
Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.
Fanout
Observability your agents can operate. Send OpenTelemetry to one binary, then investigate with Fanout's built-in agent or connect your own over MCP.
Fanout keeps OpenTelemetry traces, logs, and metrics in one binary and one data directory, with no external storage services to operate. Fanout is pre-release and changes without migration paths; the browser client, built-in agent, MCP tools, dashboards, and alerts are preview capabilities (status). Start with the documentation or run it below.
- OTLP ingest over gRPC and HTTP, with local Parquet storage and DuckDB analytics.
- An investigation agent that answers questions about your telemetry in plain language.
- An MCP server for external agents using the same typed query tools.
- Dashboards across traces, logs, and metrics, and alerts on service error rate, latency, throughput, and log volume.
Quick start
Docker
docker run --name fanout --restart unless-stopped -p 7520:7520 \-v fanout-data:/var/lib/fanout/data \ -e FANOUT_AUTH_CODE_SECRET=$(openssl rand -hex 32) \ labstack/fanout:latest
Open the one-time setup URL printed by the container and create the first administrator. Fanout displays the ingest token exactly once; save it with your collector secrets. For later sign-in without SMTP, mint a 15-minute, single-use link against the running container's control database:
docker exec fanout fanout login-link admin@example.comThe UI, API, MCP, and both OTLP transports share port 7520. See installation for image defaults and bind-mount ownership, and first boot for setup and SMTP login.
Native binary
Install a checksum-verified release for Linux or macOS, amd64 or arm64:
curl -fsSL https://raw.githubusercontent.com/labstack/fanout/main/scripts/install.sh | shexport FANOUT_AUTH_CODE_SECRET=$(openssl rand -hex 32) fanout
Set FANOUT_VERSION to a release tag, such as v2026.10.23-alpha, to pin a release, and FANOUT_PREFIX to choose the installation directory. Native installs bind 127.0.0.1:7520; set FANOUT_ADDR=:7520 for remote access, then follow the same first-boot setup.
Send telemetry
A standard OTLP/HTTP exporter can use the saved ingest token:
export OTEL_EXPORTER_OTLP_PROTOCOL=http/protobufexport OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:7520 export OTEL_EXPORTER_OTLP_HEADERS="authorization=Bearer%20$INGEST_TOKEN"
For a Collector on the same private container network, the forwarding side is:
exporters:otlp_http/fanout: endpoint: http://fanout:7520 headers: Authorization: "Bearer ${env:INGEST_TOKEN}"
service: pipelines: traces: { receivers: [otlp], exporters: [otlp_http/fanout] } metrics: { receivers: [otlp], exporters: [otlp_http/fanout] } logs: { receivers: [otlp], exporters: [otlp_http/fanout] }
Use an existing otlp receiver, set INGEST_TOKEN, and replace fanout with the Collector's reachable private hostname. OTLP/gRPC uses localhost:7520 locally; see send telemetry for TLS and HTTP/2 setup.
Enable chat
Select FANOUT_AI_PROVIDER=anthropic and inject ANTHROPIC_API_KEY, or select FANOUT_AI_PROVIDER=openai and inject OPENAI_API_KEY, then restart Fanout; the selected provider requires its key at startup. With no provider, chat is disabled and the other features still work. See AI settings.
Connect an MCP client
Set FANOUT_PUBLIC_URL to your stable, externally reachable HTTPS origin, then point a remote MCP client at that origin's /mcp endpoint. The client discovers and registers through OAuth; you authorize its scopes in the browser. Fanout serves MCP 2026-07-28 and, through the initialize handshake, 2025-11-25 and 2025-06-18 over Streamable HTTP. See connect over MCP for setup and permissions.
How it compares
| If you use | Where Fanout differs |
|---|---|
| Grafana with Loki, Tempo, and Mimir | That stack keeps a service and a query language per signal, plus object storage underneath. Fanout keeps one process, one data directory, and one typed contract across all three signals, at the cost of the horizontal scale those components are built for. |
| SigNoz | Both are OTLP-native and self-hosted. SigNoz composes a collector, ClickHouse, and query services; Fanout compiles ingest, authoritative Parquet storage, indexed trace reads, DuckDB analytics, alerting, and the browser client into one binary. |
| Jaeger | Jaeger covers traces and expects a storage backend you run separately. Fanout ingests traces, logs, and metrics into the same store, with nothing else to deploy. |
| Prometheus with Grafana | Prometheus pulls metrics and is excellent at them. Fanout accepts pushed OTLP for all three signals and is built around investigating a specific incident rather than maintaining long-range metric series. |
| Datadog, Honeycomb, Grafana Cloud | Those are managed services: someone else runs the storage, the scaling, and the upgrades, and your telemetry leaves your network to get there. Fanout is a binary you run, on data that stays on your disk. |
| An OpenTelemetry Collector piped into ClickHouse | The same shape, assembled by hand: collector, database, dashboards, and the glue between them. Fanout is that assembly as one program, with an agent and an MCP server already wired to the same query contract. |
Fanout is a single node. It has no clustering, no replication, and no object tier; a deployment that outgrows one machine's disk and CPU has outgrown Fanout.
Architecture
One process contains ingest, storage, query, alerts, the agent, MCP, and the React client. Browser and agent clients share a typed observability contract.
Parquet holds telemetry, DuckDB query state is rebuildable, and SQLite holds transactional product state. See how storage works for durable ingest, indexed reads, and compaction while reads continue.
Configuration
Configuration is environment-only: built-in defaults followed by nonempty process environment values, validated before data files or listeners open. Settings are read once at startup; every change requires a restart.
| Environment variable | Default | Purpose |
|---|---|---|
FANOUT_ADDR | 127.0.0.1:7520 | UI, API, MCP, and both OTLP transports |
FANOUT_DATA_DIR | ./data | Parquet, query state, and control SQLite |
FANOUT_AUTH_MODE | local | Login link or SMTP, or oidc |
FANOUT_AUTH_CODE_SECRET | — | Required in local mode, 32+ characters |
FANOUT_AI_PROVIDER | — | Empty disables chat; anthropic or openai enables it |
ANTHROPIC_API_KEY | — | Required for Anthropic chat |
OPENAI_API_KEY | — | Required for OpenAI chat |
FANOUT_RETENTION_DAYS | 30 | Telemetry retention window |
FANOUT_MCP_ENABLED | true | Serve the MCP endpoint at /mcp |
Every secret accepts _FILE instead of its value; see the settings reference for validation and runtime secret delivery for deployment examples.
Advanced DuckDB sizing
Fanout sizes DuckDB automatically; measured workloads can override memory, connections, and threads as described in DuckDB sizing.
For TLS, health checks, backups, upgrades, retention, and recovery, see the operator runbook.
Performance
Fanout v2026.10.8-alpha accepted 415,859 mixed OpenTelemetry items/s over 303.5 seconds on a Hetzner Cloud ccx33 (8 dedicated vCPUs, 32 GB RAM), with telemetrygen on a separate ccx33. The ingest run on 16 October 2026 passed every quality gate. See the performance methodology. Fanout Bench reproduces the measurement on your hardware.
Build from source
- Go 1.27.3 and a C/C++ toolchain on native Linux or macOS, amd64 or arm64. Build with
just buildorbash scripts/with-duckdb.sh go build ./cmd/fanout; the wrapper supplies DuckDB's pinned headers, static libraries, and CGO flags. The first build needs network access to download the checksum-verified engine. - [Bun](https://bun.sh) — compiles the browser assets
- Node.js 24.19.0 — runs development helpers and builds the documentation site
- [just](https://just.systems) — task runner
- A 32-character authentication code secret
git clone https://github.com/labstack/fanout.gitcd fanout just install # browser dependencies and git hooks just build # browser assets, then the binary
Run it with the minimum configuration:
export FANOUT_AUTH_CODE_SECRET=$(openssl rand -hex 32) # must be 32+ characters./bin/fanout
Open http://localhost:7520 and follow first-boot setup. SMTP and chat are optional; without SMTP, run ./bin/fanout login-link admin@example.com with the same configuration and data directory.
Development
Run just to list recipes, just check for the full gate, just test for Go tests, and just ui to rebuild embedded browser assets. See CONTRIBUTING.md for environment setup, generated assets, hooks, and project layout.
Releases
Versions are CalVer — vYYYY.M.N[-alpha|-beta|-rc], numbered from 0 within each month across all maturity suffixes. Fanout is alpha (for example, v2026.10.23-alpha); GA has no suffix. Container tags omit the leading v, and every release moves latest. Tagged releases publish identical manifests to Docker Hub (labstack/fanout) and GHCR (ghcr.io/labstack/fanout); GHCR is canonical and also carries development images.
| Image tag | Points at |
|---|---|
labstack/fanout:latest | the newest release, mirrored on Docker Hub |
labstack/fanout:2026.10.23-alpha | that exact release, mirrored on Docker Hub |
ghcr.io/labstack/fanout:latest | the newest release |
ghcr.io/labstack/fanout:2026.10.23-alpha | that exact release |
ghcr.io/labstack/fanout:main | the tip of main |
ghcr.io/labstack/fanout:sha- | one specific commit |
See docs/release.md for platforms, checksums, provenance, and verification.
C
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