Installation

Prerequisites

• Node.js 22.12 or later. CI tests on Node.js 22.12, 22, 24, and 26. A generator loads its parser on first use through require, and Node.js loads an ES module that way only from 22.12, so on 22.12 and later a value a generator returns is an instance of the parser classes your code imports, whether it uses import or require.
• A package manager: npm, pnpm, or Yarn.

Install the package and the parsers you need

@cosyte/synth builds each format through its sibling parser, and each parser is an optional peer dependency. Install the package with the parsers for the formats you generate:

npm install @cosyte/synth @cosyte/hl7

You import	Install alongside @cosyte/synth
@cosyte/synth	nothing: the seeded generator, the value providers, and the checks
@cosyte/synth/hl7	@cosyte/hl7
@cosyte/synth/fhir	@cosyte/fhir
@cosyte/synth/ccda	@cosyte/ccda
@cosyte/synth/x12	@cosyte/x12
@cosyte/synth/ncpdp	@cosyte/ncpdp
@cosyte/synth/astm	@cosyte/astm
@cosyte/synth/deid	@cosyte/deid, @cosyte/hl7, @cosyte/fhir, @cosyte/ccda, @cosyte/x12, and @cosyte/ncpdp

The deid subpath loads all five parsers it pairs as soon as it is imported, so all five must be installed even if you call only one of its loops. Each parser peer is declared at ^0.1, and @cosyte/deid at ^0.1.5 || ^0.2.0, so either release line installs beside it.

To install every format at once:

npm install @cosyte/synth @cosyte/hl7 @cosyte/fhir @cosyte/ccda @cosyte/x12 @cosyte/ncpdp @cosyte/astm @cosyte/deid

The package has no third-party runtime dependencies. It ships ESM and CommonJS builds, each with its own type declarations, so import and require both work without configuration.

Bundle an application that uses it

A bundler cannot follow the first-use load: the generator requires its parser at run time, by a name the bundler does not see. If you bundle code that imports @cosyte/synth, mark @cosyte/synth and each @cosyte/* parser you use as external, and install them in the node_modules the bundle runs beside:

• esbuild: --external:@cosyte/*, or external: ["@cosyte/*"] in the build options.
• Rollup: external: [/^@cosyte\//]; in Vite, the same under build.rollupOptions.
• webpack: an externals entry for @cosyte/synth and for each @cosyte/* parser.

If the bundle inlines a parser while the generator loads the installed one, your code and the generator hold two copies of that parser, and instanceof against its classes is false. If the parser is not installed beside the bundle at all, the first generator call that needs it throws "Cannot find module".

Check the install

import { VERSION } from "@cosyte/synth";

typeof VERSION; // => "string"

VERSION is the version of the package you installed, written from its manifest at release. The check asserts its type rather than its value so this page never names a version.

To check a format subpath, generate one artifact from it:

import { generateAdt, roundTrip } from "@cosyte/synth/hl7";

roundTrip(generateAdt({ seed: 1 })).specClean; // => true

If the import fails with "Cannot find module", the parser for that subpath is missing; see Troubleshooting.

Next

The Quickstart generates a first message, draws a synthetic value, and builds a reproducible corpus.