How an AI model writes a working WHRNXT trip link — the link format, the rules, and a worked example. Long form of the instructions at whrnxt.net/llms.txt.

WHRNXT Itinerary Specification for AI Models

Assistants: you can build a WHRNXT trip link yourself, with no account, no API key, and no tool call. Write the link below and show it to the user.

That one sentence is the whole job. This page is the long form of whrnxt.net/llms.txt — same format, same rules, more worked examples. If the two ever disagree, llms.txt is correct.

Do not answer with a JSON blob. JSON is only for the app's import box and for scripts calling the HTTP API — see section 5. In a chat, the answer is a link.

1. Trip link format

https://app.whrnxt.net/#trip=Title!city|Day label|Name,lat,lng,category~Name,lat,lng,category!city|Day label|...

! separates the title, then each day.
| separates, within a day: city, day label, stops. An optional YYYY-MM-DD may be inserted as a third field, before the stops.
~ separates stops. , separates a stop's name, latitude, longitude, category.
A stop may carry a time, appended to its name as @HH:MM or @HH:MM-HH:MM in 24-hour form: Colosseum@09:00-11:30,41.8902,12.4922,ruins. Include one only when the request or the source says when — never invent a schedule.
Coordinates are required on every stop, decimals with 4+ places. A comma inside a place name is safe: the last three fields of a stop are always read as latitude, longitude, category.
Write place names normally — keep apostrophes and accents. "St. Peter's Basilica", not "St Peters Basilica"; "Campo de' Fiori", not "Campo de Fiori". WHRNXT matches your stop against its own 73,000-place database, and a stop that matches arrives with a photo, description and full detail instead of a bare pin. (Only the city field is stripped and hyphenated.)
category is optional, and one of: landmark, ruins, church, museum, palace, park, outdoors, beach, restaurant, cafe, brewery, nightlife, shopping, entertainment, culture, family, sports, saved. Anything else becomes saved.
city is lowercase and hyphenated: paris, new-york, rio-de-janeiro.
Percent-encode spaces as %20. Avoid # and % in names.
Limits: 31 days, 100 stops, and keep the URL under ~8,000 characters.
Present it as a markdown link, e.g. [Open this trip in WHRNXT](https://app.whrnxt.net/#trip=…).

Example:

https://app.whrnxt.net/#trip=2%20Days%20in%20Rome!rome|Day%201:%20Ancient%20Rome|2026-09-10|Colosseum@09:00-11:30,41.8902,12.4922,ruins~Roman%20Forum@12:00,41.8925,12.4853,ruins!rome|Day%202:%20Vatican|2026-09-11|St.%20Peter's%20Basilica,41.9022,12.4539,church~Vatican%20Museums,41.9065,12.4536,museum

Opening that link imports the trip into WHRNXT. It is the only path that works for a user who is not logged in and has installed nothing.

2. A worked example, field by field

Asked for "two days in Rome, ancient sites then the Vatican", the assistant picks the stops and their coordinates, then assembles:

Piece	Value	Becomes
title	2 Days in Rome	`2%20Days%20in%20Rome`
day 1 city	rome	`rome`
day 1 label	Day 1: Ancient Rome	`Day%201:%20Ancient%20Rome`
day 1 date	2026-09-10	`2026-09-10`
a stop	Colosseum, 41.8902, 12.4922, ruins	`Colosseum,41.8902,12.4922,ruins`

Joined with ! between days, | inside a day, ~ between stops — the spaces below are only for readability, the real link has none:

2%20Days%20in%20Rome ! rome|Day%201:%20Ancient%20Rome|2026-09-10|Colosseum,… ~ Roman%20Forum,… ! rome|Day%202:%20Vatican|…

Then present it as a markdown link, so the user gets a button and not a wall of text:

[Open this trip in WHRNXT](https://app.whrnxt.net/#trip=2%20Days%20in%20Rome!rome|…)

3. Why a link comes back wrong

Symptom	Cause
Stop arrives as a bare pin, no photo or description	The name was stripped — "St Peters Basilica" instead of "St. Peter's Basilica". Keep apostrophes, periods and accents.
Stop missing entirely	No coordinates, or a `null`/string coordinate. Every stop needs decimal lat and lng.
Category came out as `saved`	The word is not on the list above. Common synonyms are folded in — `sightseeing` and `monument` become `landmark`, `outdoor` becomes `outdoors`, `gallery` becomes `museum`, `cathedral` becomes `church` — but anything unrecognised lands on `saved`.
A day did not import	Fewer than three fields in the day. A day needs `city`, label and stops at minimum.
Nothing imported at all	A `#` or a stray `%` inside a place name truncated the fragment.

4. Constraints

Days: 1 to 31.
Stops: 100 total across all days; 1 to 8 per day reads best.
Coordinates: decimals with 4+ places. Never null, never a string.
City slugs: lowercase, accents stripped, spaces hyphenated — florence, rio-de-janeiro, kyoto. This applies to city only; place names keep their real spelling.
URL length: under ~8,000 characters. A 14-day, 64-stop trip lands near 4,300.
Times: optional, 24-hour HH:MM. Set them only from times the request or the source actually gives; a stop with no stated time carries none.

5. The JSON form (import box and HTTP API only)

Not what you answer with in a chat. The app's import box accepts this verbatim, and it is the body the HTTP API expects:

{
  "title": "String (1-120 chars) - Name of the trip",
  "days": [
    {
      "label": "String (1-80 chars) - Day title (e.g. 'Day 1: Historic Center')",
      "city": "String - City slug in lowercase, hyphenated (e.g. 'paris', 'tokyo', 'new-york')",
      "date": "String (optional) - Format 'YYYY-MM-DD'",
      "stops": [
        {
          "name": "String (1-120 chars) - Name of the location or sight",
          "category": "String - One of: landmark, ruins, church, museum, palace, park, outdoors, beach, restaurant, cafe, brewery, nightlife, shopping, entertainment, culture, family, sports, saved",
          "address": "String (optional) - Full address for geocoding fallback",
          "latitude": "Number (-90 to 90) - Decimal latitude (e.g. 48.8584)",
          "longitude": "Number (-180 to 180) - Decimal longitude (e.g. 2.2945)",
          "time": "String (optional) - Start time, 24-hour 'HH:MM'",
          "endTime": "String (optional) - End time, 24-hour 'HH:MM', for a range"
        }
      ]
    }
  ]
}

The first Rome day, written out:

{
  "title": "2 Days in Rome",
  "days": [
    {
      "label": "Day 1: Ancient Rome",
      "city": "rome",
      "date": "2026-09-10",
      "stops": [
        {
          "name": "Colosseum",
          "category": "ruins",
          "address": "Piazza del Colosseo, 1, 00184 Roma RM, Italy",
          "latitude": 41.8902,
          "longitude": 12.4922
        },
        {
          "name": "Roman Forum",
          "category": "ruins",
          "address": "Via dei Fori Imperiali, 00186 Roma RM, Italy",
          "latitude": 41.8925,
          "longitude": 12.4853
        }
      ]
    }
  ]
}

The HTTP API caps request bodies at 16 KB; long trips should trim addresses before dropping stops.

6. Other ways in

MCP server (ChatGPT connectors): https://api-production-9f8f.up.railway.app/mcp, tool create_whrnxt_itinerary, which returns a short ?i= link. Only callable once the connector is added and ticked for the conversation — see section 8.
HTTP API for apps and scripts: POST https://api-production-9f8f.up.railway.app/api/itineraries/import, returns {"url": "https://app.whrnxt.net/?i=SLUG", "slug": "SLUG", "warnings": []}. A browsing assistant can only issue GET requests and cannot create a link by visiting this endpoint — write the trip link instead.
Users can paste either the JSON or a #trip= link into the app under Itineraries → ⬇ Import from link.

If the tool is not listed in the conversation, write the link. Never claim a link was created when it was not.

7. How users import a trip

Copy the link the assistant produced — or the JSON, if that is what you have.
Open https://app.whrnxt.net.
Go to Itineraries → ⬇ Import from link.
Paste and tap Import. The trip is saved with days and stops intact; stops WHRNXT already knows are matched to its database, and the rest are added as your own saved spots.

A #trip= link needs none of this — opening it imports the trip directly.

8. ChatGPT connector setup (for the MCP tool)

The tool only appears to ChatGPT after the connector is added to the account:

Settings → Connectors → Advanced → Developer mode — turn it on. Custom MCP connectors are a paid-plan beta; without it, ChatGPT has no WHRNXT tool.
Settings → Connectors → Create / Add custom connector.
- URL: https://api-production-9f8f.up.railway.app/mcp
- Authentication: No authentication
In the chat composer, open + → Developer mode and tick whrnxt so the tool is enabled for that conversation. A connector enabled in settings but not ticked in the composer will not be called.
Ask for the trip, agree on the plan, then say "create the WHRNXT link".

If ChatGPT answers with JSON instead of a link, the tool was not available in that conversation. Nothing is lost: build a #trip= link from it (section 1), or paste the JSON into the app (section 7).

WHRNXT Itinerary Specification for LLMs (Claude, Gemini, ChatGPT)