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OnlyWorlds

Defines a JSON/YAML schema for fictional world elements and serves them through an API that editors and game engines read and write.

WritingSDKAPIOpen source
onlyworlds.com ↗GitHubYouTube
At a glanceswept 2026-10-13

≈ 8visits/mo

Emerging · estimate, read 2026-10-13

For
Worldbuilders and developers who want characters, places and stories kept in one shared, open world format across tools.
Price
Price not read
Activity
Actively maintainedrelease 2 days ago
Company
Domain since 2020domain registered
Runs as
SDKAPI
AlternativesSet it up for my teamIs OnlyWorlds yours? Claim the card →
What people do with it
  • write and map a fictional world in Atlas
  • sync world elements with Obsidian notes
  • browse a world inside a Unity game editor
The companyeach fact with its source · read 2026-10-14
  • Domain since2020domain registered
Your datawhat they publish, each line with its page · read 2026-10-14

These are OnlyWorlds's own statements, read from its pages. We did not audit them. A line that is missing was not found on the pages we read; it does not mean the practice is absent.

How a program reaches itfound, not claimed · read 2026-10-14
  • MCP servercom.onlyworlds/mcpverified in the MCP registry
  • Stateanswers, 12 toolschecked 2026-10-14
  • Address to connectwww.onlyworlds.com/mcp
  • API docsonlyworlds.com/developthe vendor's page ↗

MCP server details →

Each line is something a program found when it went looking: the registry entry, the server's own answer, a spec that parses. A missing line means we did not find it, not that it does not exist.

Most used in Writingby use, among tools still maintained — this tool shares no tags yet

Figure and bar: visits/mo, estimate · year: online since

All Writing tools →

Questions this page answers
  • What is OnlyWorlds?

    Defines a JSON/YAML schema for fictional world elements and serves them through an API that editors and game engines read and write. It is listed in the Atlas under Writing.

  • Who is OnlyWorlds for?

    Worldbuilders and developers who want characters, places and stories kept in one shared, open world format across tools.

  • Do people use OnlyWorlds?

    Emerging: ≈ 8 visits/mo · estimate, 2026-10 · 2.3k installs/mo (npm).

  • Is OnlyWorlds still maintained?

    Actively maintained: release 2 days ago.

  • Is OnlyWorlds safe?

    We do not audit vendors. What OnlyWorlds publishes, read 2026-10-14: GDPR, CCPA stated on its privacy policy.

Not quite it? Describe the job

beta

Five tools from the Atlas that fit it, each judged against what you wrote.

How we read a tool

No votes, no reviews, no vendor claims. Every week a crawler reads each tool's own site and a few public registries, and the words on the card are bands over what it read.

  • Use: visits to the site (estimated), installs from npm and PyPI, presence in Chrome's usage report.
  • Activity: the newest release on GitHub, npm or PyPI; the newest dated page on the site; open roles on a public jobs board.
  • Price: the vendor's own pricing page, read with the date. A figure is printed only when it is on that page.
  • The line and the use cases are written by us from the homepage, one tool at a time, and refused when they repeat the vendor's marketing.

How AI assistants read each site — the reading vendors ask us about — is on each tool's own visibility page.