TypeScript 7

TypeScript 7 is the native port of the compiler. Its typescript package has no JavaScript API: there is no ts.factory and no printer. openapi-typescript 7 builds every type with ts.factory and prints it with the TypeScript printer, so it cannot run in a project that installs TypeScript 7.

openapi-typesafe builds types as its own small tree and prints them itself. It needs no typescript package, so it runs next to TypeScript 7, 6 or 5.

The errors

If you landed here from a search, these are the errors openapi-typescript 7.13 gives with typescript 7.0.

When installing

npm refuses to install, because openapi-typescript has a peer dependency on TypeScript 5:

npm error code ERESOLVE
npm error ERESOLVE unable to resolve dependency tree
npm error
npm error While resolving: my-project@1.0.0
npm error Found: typescript@7.0.2
npm error node_modules/typescript
npm error   typescript@"7.0.2" from the root project
npm error
npm error Could not resolve dependency:
npm error peer typescript@"^5.x" from openapi-typescript@7.13.0

pnpm installs, with a warning; pnpm peers check shows the cause:

✕ unmet peer typescript
  Installed: 7.0.2
  Wanted:
    ^5.x:
      openapi-typescript@7.13.0

When generating

With --legacy-peer-deps, --force, pnpm, or any other way past the install, the CLI and the Node API both crash as soon as the module loads:

file:///…/node_modules/openapi-typescript/dist/lib/ts.mjs:11
const BOOLEAN = ts.factory.createKeywordTypeNode(ts.SyntaxKind.BooleanKeyword);
                           ^

TypeError: Cannot read properties of undefined (reading 'createKeywordTypeNode')

Pinning typescript to 5.x or 6.x for the whole project is the only fix within openapi-typescript.

The fix

Switch to openapi-typesafe. It is a drop-in successor: the same flags, Node API and types (only the header comment differs).

npx openapi-typesafe-migrate --write

See the migration guide for what the tool changes and the one regenerated-file commit it needs.

Callbacks that use TypeScript nodes

The Node API options transform, postTransform and transformProperty may build types with ts.factory, as in openapi-typescript. Such callbacks still need a TypeScript JavaScript API. In a TypeScript 7 project, install TypeScript 6 under its own name next to it:

npm i -D @typescript/typescript6

npm links tsc to TypeScript 6

@typescript/typescript6 depends on @typescript/old (TypeScript 6), which also has a tsc command. npm puts that one in node_modules/.bin, so npx tsc and the tsc of your scripts run TypeScript 6.0 without a warning. pnpm and bun keep TypeScript 7. With npm, also install TypeScript 7 under a name that npm links first:

npm i -D @typescript/native@npm:typescript@7

Check with npx tsc -v.

Without typescript 6 or earlier, and without @typescript/typescript6, the run fails with an OpenAPITypesafeError whose code is TYPESCRIPT_NOT_FOUND:

A callback or helper uses TypeScript compiler nodes, which needs the TypeScript JavaScript API. Install "typescript" version 6 or earlier, or "@typescript/typescript6" on TypeScript 7, or use IR callbacks (irCallbacks: true).

The better fix is to move the callbacks to IR callbacks, which need no compiler: with irCallbacks: true, a callback returns plain type text such as "Date | null". The migration tool rewrites a transform that only returns ts.factory types for you.

Type-checking the declarations

The package's declarations type-check with TypeScript 7 and skipLibCheck: false. The types of the compiler-node forms (ts.Node, ts.TypeNode and the others in the transform, postTransform and transformProperty options, astToString and the ts* helpers) are read from the typescript package you have installed. With TypeScript 5 or 6 they are its own node types. TypeScript 7 has no node types, so there they are any: a callback that builds nodes with @typescript/typescript6 compiles, and the IR callbacks (irCallbacks: true) keep their full types.

Four errors remain with skipLibCheck: false, on every TypeScript version, and come from the schema loader, @redocly/openapi-core 1.34. Its declarations import json-schema-to-ts and js-yaml, whose types it does not install:

node_modules/@redocly/openapi-core/lib/config/types.d.ts(6,33): error TS2307: Cannot find module 'json-schema-to-ts' or its corresponding type declarations.
node_modules/@redocly/openapi-core/lib/js-yaml/index.d.ts(1,47): error TS7016: Could not find a declaration file for module 'js-yaml'.

openapi-typescript 7.13 has the same errors. Install the two as development dependencies (npm i -D json-schema-to-ts @types/js-yaml), or keep skipLibCheck: true.