atlashot — data on maps, from a link

Turn {region: value} data into a shareable choropleth map image with a single GET URL. No account, no API key, no code execution.

URL anatomy

https://atlashot.pages.dev/m?map=<mapset>&d=<CODE:value,...>&title=...

Append &format=svg for the raw SVG image (directly embeddable), or &format=json for machine-readable diagnostics.

Parameters

param	required	type	default	allowed	meaning
`map`	yes	string	—	a map set id from the table below (e.g. world, europe, us, ro)	Which map to draw.
`d`	yes	string	—	comma-separated CODE:value pairs	The data. CODE is ISO 3166-1 alpha-2 for countries (DE, FR) or ISO 3166-2 for subdivisions (US-CA, RO-CJ). Values: numbers for color scales, or short text labels for categorical maps. Aliases accepted per map set: plain region names everywhere; ISO alpha-3 + ISO numeric (world, europe); EL/UK NUTS-0 (europe); FIPS numeric + bare postal (us); NUTS-3 codes + bare county codes (ro).
`title`	no	string	none	any text (URL-encoded, + for space)	Map title, rendered into the image.
`subtitle`	no	string	none	any text	Smaller line under the title.
`unit`	no	string	none	any short text	Unit label shown with the legend (e.g. EUR/MWh, %).
`source`	no	string	none	any short text	Data source credit, rendered next to the attribution.
`palette`	no	string	blues (numeric), rdbu (mixed-sign), tableau (text)	blues, greens, oranges, purples, reds, viridis, rdbu, brbg, puor, tableau	Color palette. Sequential for all-positive numbers, diverging (rdbu/brbg/puor) for mixed-sign, tableau for categories.
`scale`	no	string	quantile (quantize over a symmetric domain for mixed-sign data)	quantile, quantize, linear, threshold:10,20,50	How values map to color classes. threshold takes explicit cut points.
`classes`	no	integer	5	3–9	Number of color classes.
`domain`	no	string	data min,max (symmetric around 0 for mixed-sign data)	min,max (two numbers)	Override the scale extent.
`format`	no	string	,.2~f	a d3-format specifier (.1f, .0%, ~s) — or the reserved values json and svg	Number format for legend labels. Reserved values change the response instead: format=json returns machine-readable diagnostics (application/json); format=svg returns the map itself as a raw SVG image (image/svg+xml), directly embeddable in <img> tags.
`embed`	no	flag	0	1	Render only the map (for iframes) — no page chrome.
`v`	no	integer	1	1	URL format version.

Map sets

id	coverage	regions	region codes
`world`	World — countries	175	codes
`europe`	Europe — countries	46	codes
`us`	United States — states	51	codes
`ro`	Romania — județe	42	codes

Examples

European electricity prices (sequential scale, unit)

Country codes are ISO alpha-2; unit shows in the legend.

https://atlashot.pages.dev/m/?map=europe&title=Electricity+prices+2026&unit=EUR/MWh&source=ENTSO-E&d=AT:241,BE:189.5,DE:210,FR:198,PL:150,ES:165,IT:220,NL:195,SE:96,NO:88

World temperature anomaly (diverging, mixed-sign)

Mixed-sign values pick the diverging red-blue palette automatically.

https://atlashot.pages.dev/m/?map=world&title=Temperature+anomaly&unit=%C2%B0C+vs+1991-2020&d=US:1.2,CA:1.8,RU:2.1,BR:0.6,AU:0.9,IN:0.7,CN:1.1,ZA:0.8,AR:-0.2,GL:2.9

US states, categorical values

Text values make a categorical map; codes are US-XX.

https://atlashot.pages.dev/m/?map=us&title=Time+zones&d=US-CA:Pacific,US-NV:Pacific,US-CO:Mountain,US-TX:Central,US-IL:Central,US-NY:Eastern,US-FL:Eastern

Romanian counties with explicit thresholds

Subdivision codes are RO-XX; threshold sets the class cut points.

https://atlashot.pages.dev/m/?map=ro&title=Population+density&unit=per+km%C2%B2&scale=threshold:50,100,200&d=RO-B:8093,RO-CJ:105,RO-TM:80,RO-IS:146,RO-CT:96,RO-BV:115

Percent-formatted, fixed domain

format styles legend labels; domain fixes the scale extent.

https://atlashot.pages.dev/m/?map=europe&title=Renewables+share&scale=quantize&format=.0%25&domain=0,1&d=NO:0.98,SE:0.68,FR:0.25,DE:0.46,PL:0.21,ES:0.5

Instructions for AI agents

Region codes are ISO codes, not names: RO-CJ not "Cluj county", US-CA not "California" — names usually resolve as a courtesy, but ISO codes are the contract. Do not invent codes.
Subdivision codes include the country prefix: US-CA, RO-CJ — never bare CA or CJ in documentation examples (bare forms resolve, but are ambiguous across map sets).
Do not invent parameters. The full list is above; anything else is ignored with a warning.
Keep URLs under 2,000 characters (hard limit 4,000). Every listed map set fits comfortably: a full world dataset is ~1,600 characters.
Values are plain numbers (189.5) or short text labels (high) — no percent signs, no thousands separators, no quotes inside d=; labels must not contain , ; : = or newline characters (the d= grammar reserves them).
Use commas between pairs and a colon inside each pair: d=DE:83.2,FR:68.6 — spaces are allowed but must be URL-encoded (+).
The URL is data, not code: never base64/deflate the payload; write it out plainly.
Avoid characters that break URL auto-detection in chat and markdown — parentheses, quotes, trailing punctuation — in free-text values like title and source: a bare ) usually truncates the link where you paste it. Percent-encode them (%28 %29) or leave them out.
To verify a URL before sharing it, append &format=json and fetch it: the response is real JSON (application/json) reporting ok, matched/total, unmatched codes with suggestions, and a corrected example. HTTP 400 means required parameters are missing or wrong.

Errors and diagnostics

Rendering is forgiving: bad rows are skipped with a warning, the rest of the map renders. Append &format=json to any map URL for a true JSON diagnostics report (HTTP 200 when the map renders, 400 when required parameters are missing or wrong).