viafrei

Live German traffic, rail, parking, charging, fuel, addresses and weather — inside your AI assistant. Ask in plain German or plain English and the answer comes back from official open data, with the attribution the licence requires.

npx viafrei

No account, no API key, no sign-up.

Ask your assistant things like

Welche Züge fahren als Nächstes ab Hamburg Hbf?

Abfahrten ab Hamburg Hbf (nächste 60 Minuten):
12:28 RJ 384 → Koebenhavn H, Gleis 5, pünktlich
12:29 ICE 7 → Karlsruhe Hbf, Gleis 14, pünktlich
12:33 ICE 774 → Kiel Hbf, Gleis 11, pünktlich
12:33 ME RB31 → Lüneburg, Gleis 13A-C, pünktlich
12:34 ICE 601 → München Hbf, Gleis 8A-F, pünktlich

Stand 12:23 · Quelle: Fahrplandaten: Deutsche Bahn AG, DB API Marketplace,
CC BY 4.0, bearbeitet (…) · Bahnhofsdaten: Deutsche Bahn AG,
DB API Marketplace, CC BY 4.0, bearbeitet (…)

That is a real answer, not a mock-up: it came back from https://mcp.viafrei.de/mcp on 2026-09-27 at 12:23 Berlin time. Two edits, both named: the two source URIs are shortened to … for the reason in the next paragraph, and only the first five of the ten departures it returned are shown. The server sends no "… and five more" line — the truncation is this page's, not its.

Every answer ends with a line like that last one. It is the licence talking, and it is meant to be shown to whoever reads the answer — see Using the data you get back. Reproduce the line the server sends you, not this one: it has been shortened here, and the real one names each source's URL, which the licence requires you to keep.

ViaFrei is in its stabilisation and testing phase at the time of writing: live and free, with some sources thinner than they will be, and the occasional tool that answers slowly or not at all. Tell us when that happens — open an issue with what you asked and what came back. The server necessarily sees the question, and sees it fail; what it cannot see is that an answer was useless to you (see What it does not do).

Plain German or plain English, whichever you speak — the answers come back in the language you asked in, not translated from one house language:

• Gibt es gerade Stau auf der A8?
• Find a rest area with lorry parking on the A9
• Sind auf der A8 Baustellen geplant, wenn ich nächste Woche fahre?
• Wo kann ich in Leipzig mit Typ 2 laden?
• Gibt es eine Unwetterwarnung für Freiburg?
• Brauche ich in Deutschland eine Umweltplakette?
• Funktioniert der Aufzug am Bahnhof Köln Messe/Deutz? — lift and escalator status, which is the difference between a station being usable and not
• Wo ist die nächste Apotheke zum Leipziger Hauptbahnhof?
• What is at 52.5163, 13.3777? — and the other direction: a street address to coordinates
• Tell me when the A8 reopens — the server can watch a situation and tell your assistant when it changes, so you need not keep asking. The watch lives in the conversation that opened it: it reaches no inbox and no phone, and it ends with the session. Three hours by default; 24 is the longest one can be asked to run

What it covers

Eighteen tools as of this release. Grouped by the question they answer, because the grouping is stable and a pasted catalogue is not:

| | | |---|---| | Roads | live incidents, jams and closures; roadworks ahead on a route; the state of one Autobahn end to end; lorry parking on the motorways, with occupancy wherever the operator publishes it — see the note below on car parks | | Rail | next departures from any station with real-time delays and platforms; how punctual public transport is across a region right now (region-wide — never one line, trip or stop); whether a station's lifts and escalators are working right now | | Energy | charging points by connector type and power; the cheapest fuel near a place | | Places | a street address to coordinates and back; points of interest; what is at a coordinate, and what is near it — nationwide, all sixteen Länder (measured on 2026-09-27 — how) | | Weather | official DWD severe-weather warnings for a place | | Watches | ask once and be told when a situation changes, instead of asking again |

One thing the parking row does not yet cover: car parks. The licence for station car parks is read and the loader exists, but nothing on the public service answers with one today — asked for a car_park in Köln, Hamburg and Leipzig on 2026-09-27, every facility that came back was a lorry park or an unclassified site, and none carried occupancy. So what you get from find_parking today is motorway lorry parking. The table said "car and lorry parking" until this release; it was the same over-claim the Rail row carried about disruptions, and it is corrected here rather than left for a user to discover.

No tool names, descriptions or schemas are written by hand on this page, on purpose. This file is frozen inside a published tarball and cannot be corrected without a release, so a hand-copied catalogue would start rotting the first time a description changed on the server.

API.md is the way round that, and it is honest about what it is. It is generated from catalogue.json — a snapshot of what the production server answered when asked to describe itself — and CI fails if the two have drifted, so the document cannot quietly disagree with the snapshot. What that does not fix is the snapshot ageing relative to the live server: a capture is a point in time, and API.md's header carries the date it was taken. The source of truth is still the running server: connect any MCP client and call tools/list. (https://viafrei.de is the live national traffic digest, not a catalogue.)

Connect in one line

The product is a hosted MCP server. There is nothing to deploy, no key to request and no quota to negotiate — point a client at it and the tools appear.

Streamable HTTP — the address to use. Most clients speak this, and they need none of the rest of this page:

https://mcp.viafrei.de/mcp

claude mcp add --transport http viafrei https://mcp.viafrei.de/mcp

HTTP+SSE — if your client only speaks the older transport, it is answered too, so nobody meets a locked door. It is deprecated in the specification; prefer the address above:

claude mcp add --transport sse viafrei https://mcp.viafrei.de/sse

stdio — this package. Some clients still speak only stdio, and this bridge is for those, and only those. Node 22 or newer; nothing to install, because npx fetches it when your client starts it. The same three lines fit any client that takes an stdio MCP server, including the .mcp.json an IDE reads and Claude Desktop's claude_desktop_config.json:

{
  "mcpServers": {
    "viafrei": {
      "command": "npx",
      "args": ["-y", "viafrei"]
    }
  }
}

Restart the client and ask it one of the questions above.

Documentation

| | | |---|---| | API.md | Every tool with its parameters, types, defaults and constraints, plus the resources, resource templates and prompts. Generated from a dated snapshot of the running server, so the descriptions are the server's own words — which is what your assistant actually reads when it picks a tool. | | Wiki | The prose half: connecting your assistant, tools at a glance, the roadmap and an FAQ. | | SOURCES.md | Every publisher, what it covers, its licence, and the attribution line to reproduce — including the conditions that are licence breaches rather than style problems. | | SUPPORT.md | Where a question, a bad answer or a security report should go, and what makes a report easy to act on. |

Worked use cases

Five walkthroughs, each naming the tools that answer it and what comes back:

• Driving Munich to Berlin — briefing a motorway run: several A-roads in one call, roadworks ahead, a fuel or charging stop, parking at the far end.
• The commute that broke — departures, regional disruption, and a station lift that is out, which is the difference between a step-free route existing and not.
• An EV on a long weekend — charging by connector and power, low-emission-zone rules, what is around a stop.
• Fleet and logistics briefings — a dispatcher's morning brief, watches that report a change instead of being polled, and the one licence rule that bites hardest here.
• Building a local guide agent — a vague place to coordinates and back, and what OpenStreetMap's licence asks of you.

Why build on it

• One endpoint instead of a stack of integrations. SOURCES.md lists twenty-one sources from sixteen publishers — Autobahn GmbH, the national access point, Deutsche Bahn, DWD, BKG, GeoNames, OpenStreetMap, MTS-K and the rest — each with its own format, its own release rhythm and its own licence. They arrive here as one protocol and one set of tools. (Count them in that table; one of the sixteen is us.)
• The licence work is done and it travels with the answer. Every result carries the attribution line its sources require, and the ones with conditions attached say so in the result itself — share-alike is flagged, and the MTS-K purpose limit arrives as a sentence you are meant to show. You are not left to work out what you owe whom.
• It answers in the language of the question, German or English, rather than translating out of one house language.
• It is a transport shim and nothing more. The bridge holds no data and no credentials, writes no file outside the OS temp directory, and makes no decision about any answer. No telemetry, no analytics, no usage counter, no update check — see What it does not do.
• Failures are machine-readable. One line on stderr and a distinct exit code per cause, so a supervisor can tell "your network is down" from "you typed the flag wrong" without parsing English.
• Ask once, be told when it changes. A watch turns polling into a notification for as long as the conversation lives.

Free while ViaFrei stabilises, and the limits that exist are written down on this page rather than discovered in production.

Configuration

| option | what it does | |---|---| | --url <url> | endpoint to relay to. Default https://mcp.viafrei.de/mcp — see the note below | | --header "Name: value" | extra HTTP header on every request, repeatable. For an API key, when there is one | | --timeout <ms> | per-request timeout, default 30000. The event stream is never timed out | | --version, --help | print and exit |

Many MCP clients can only pass an env block, not arguments, so every option has an environment variable too:

| variable | same as | |---|---| | VIAFREI_MCP_URL | --url | | VIAFREI_MCP_HEADER | --header. Several headers are separated by a newline, which can never appear in a header name or value, so nothing you might need to send is unrepresentable — a comma, a semicolon and a space all occur inside real header values | | VIAFREI_MCP_TIMEOUT_MS | --timeout |

A flag wins over the variable; the variable wins over the built-in default. A --header of the same name replaces one from the variable, and a --header of a different name is added alongside it.

{
  "mcpServers": {
    "viafrei": {
      "command": "npx",
      "args": ["-y", "viafrei"],
      "env": { "VIAFREI_MCP_HEADER": "Authorization: Bearer …" }
    }
  }
}

There is no self-hosted ViaFrei. The server is a hosted service, so --url is not a way to run your own — it is there for a proxy or gateway in front of the service, and for the stub server this repository's test suite starts. Leave it unset and the bridge goes to the hosted endpoint, which is what you want.

When something is wrong

One line to stderr and an exit code that says what happened. No stack traces:

viafrei: cannot reach https://example.invalid/mcp: host not found (DNS) (ENOTFOUND) - check your network connection; --url only if you relay through a proxy

That line is copied from a run, exit code 3. The same text also goes back to the client as a JSON-RPC error, so an assistant can say what went wrong instead of going quiet.

| exit | meaning | |---|---| | 0 | clean shutdown (the client closed stdin, or sent SIGINT/SIGTERM) | | 1 | something else went wrong; the line says what | | 2 | bad usage — a flag or a value the bridge does not accept | | 3 | the endpoint could not be reached, stopped answering, or never answered in time | | 4 | the endpoint answered and this cannot continue: it refused (the line names the HTTP status), it forgot the session, it answered with something that is not MCP, or it redirected to another origin | | 5 | protocol version mismatch; the line names the version the server speaks |

A slow call may be a retried call. A 429, 502, 503 or 504 is tried again once — after the delay the server asked for in Retry-After, or 250 ms when it asked for none. A connection that fails outright rather than answering (reset, broken pipe, socket or connect timeout) is likewise tried once more, after the fixed 250 ms; there is no header to read on that path. Two cases are deliberately not retried, because waiting would be worse than answering: a 429 carrying no usable Retry-After, and any delay the server asks for that is longer than your timeout. Both come straight back as the ordinary failure line with the status in it. An event stream is never retried.

Your timeout bounds each request, not the call. It is attached per HTTP request, so the second attempt gets a fresh one, and so does each hop of a same-origin redirect. What you can rely on is per request: no single request outlives the timeout, and a delay longer than the timeout is never waited out at all. What follows from that is the arithmetic: two attempts plus a delay that may itself be as long as the timeout is a worst case of about three times what you set, and more than that if the endpoint redirects, since every hop is bounded separately. So no setting here caps the whole call — if you need a hard ceiling, enforce it on your side and treat the timeout as the per-request bound it is.

An established session is allowed to wobble — a dropped event stream is a warning, not an exit, and the bridge reconnects. It is not allowed to be dead in silence: several failures in a row with nothing succeeding in between end the process with the code above, so the client that started it finds out.

What it does not do

No telemetry, no analytics, no usage counter, no update check. It writes no file outside the OS temp directory, and it stores no credential — --header is passed through to the endpoint and never persisted or logged.

It also does not follow a redirect off the origin you pointed it at. Your headers go to that origin and nowhere else: a cross-origin redirect is refused with one line naming both ends, so a server cannot forward your API key somewhere you did not choose. Same-origin redirects are followed normally.

Using the data you get back

Every result carries an attribution line. Show it to the person reading the answer. The full register lives at the resource viafrei://attribution, and SOURCES.md is the readable version of it: every publisher, what they cover, the licence, and the exact attribution line to reproduce.

Two constraints matter more than the rest, because getting them wrong is a licence breach rather than a style problem:

• MTS-K fuel prices are consumer information only. No redistribution in any form — that includes aggregates, comparisons, price tables and anything derived. Answer the person who asked; do not build a product out of it.
• DELFI public-transport data is Creative Commons Attribution-ShareAlike. Share-alike travels with anything you derive from it — recompute it, reshape it, rearrange it, build a delay table out of it, and that is Adapted Material you must license under BY-SA (art. 1(a) names material "translated, altered, arranged, transformed, or otherwise modified"). Merely showing it beside another source's data is an aggregation, and puts no obligation on the other source; an earlier version of this page said otherwise, which told you a licence forbids something it permits. The catalogue record for the realtime feed names no licence version, so do not rely on one for a derivative — SOURCES.md has the detail and the open question.

Everything else — where each answer comes from, and what each licence asks of you — is in SOURCES.md. See also NOTICE and LICENSE.

The server itself

The MCP server is offered as a hosted service, and its source is closed. It is not in this repository and is not published. What is public is the part that is meant to be: the tool names, their descriptions, their input schemas, the shape of the results and the attribution lines — everything a client reads from tools/list, which is the product surface.

This is said plainly so nobody spends an evening looking for the server code.

Contributing

Yes, please — see CONTRIBUTING.md and CODE_OF_CONDUCT.md. Issues and discussions are open. The bridge is small and self-contained, which is exactly what makes it a reasonable thing to send a first patch to.

One issue template is worth knowing about before you need it: the answer was wrong or useless. A tool that fails is something the server sees; a tool that answers confidently with the wrong thing is not. That report is the one thing we cannot get any other way.

Security

Never open a public issue for a key, a token or anything that looks like one. See SECURITY.md for the private reporting path.

Licence

Apache-2.0 for this code. Data obtained through the server keeps its provider's licence — see NOTICE.