Published by Voxgig, which makes one of the two tools compared here. Facts checked against the first-party sources linked below. Corrections go to info@voxgig.com. Every page in this section follows the same scope and method.
OpenAPI Generator is a community fork of Swagger Codegen, made in 2018 when most of the maintainer group left the original project. It is Apache 2.0, governed by a core team with a technical committee per language, and published to Maven Central on a regular release cadence.
Calling it a generator undersells it. It is a framework hosting around a hundred generators: client libraries in more than 40 languages, server stubs for more than 20 frameworks, plus documentation, Postman collections, Protobuf schemas, GraphQL, JMeter and k6 scripts, and build configuration. Each generator is a Java class plus a tree of Mustache templates, and each has its own maintainers and its own maturity.
You configure it with command-line options, a config file, and template overrides: copy the templates out, edit them, point the CLI at your directory. It runs on the JVM, or from a Docker image, or through Maven, Gradle and npm wrappers.
The scale shows in the issue tracker. As of 28 September 2026 the repository showed over five thousand open issues and several hundred open pull requests. That number describes a hundred generators of different ages and different levels of maintenance sharing one tracker, rather than the health of any one of them. The practical consequence is that experience varies by which generator a project lands on.
Capabilities OpenAPI Generator has that Voxgig does not, in enough detail to evaluate them.
If you need Elixir, Perl, Rust, Scala, Erlang, PowerShell, Ada or Apex, this is often the only tool that has a generator for it. Voxgig has 23 language targets against a list roughly four times longer. Where the deciding question is whether a target exists at all, OpenAPI Generator is the widest net available.
Spring, FastAPI, Gin, Laravel, ASP.NET, Express, and about fifteen more. Generating the server skeleton from the same description as the client suits design-first API work. Voxgig generates no server-side output at all, so a team that needs a stub has no decision left to make here.
Extract the templates for your generator, edit them, and pass -t ./templates. There is no supported extension model to work within and no upgrade story for what you change, but there is also nothing you cannot change. Long-lived template forks are common, which suggests the mechanism's simplicity offsets the absence of an upgrade path for many teams.
Apache 2.0, a technical committee, artifacts in Maven Central for every release since 2018. Three of the tools compared here changed owner in the ten months to May 2026, and one stopped taking new projects the day it was announced. A community-governed Apache 2.0 project with published artifacts cannot be withdrawn the same way, which is the relevant property for procurement and for long-lived builds.
A jar, or a Docker image. No sign-in, no telemetry to switch off, no seat count, and no network call at generation time, which is what a regulated or disconnected build environment needs. Voxgig, Kiota and Hey API have the same property, and since September 2026 so does the AGPL path of Speakeasy's generator. Fern's local generation checks in with a Fern API key, and every SDK language in Cloudflare Forge, TypeScript included, runs a Fern generator in Docker; APIMatic, liblab and Stainless generate on their own services.
No partial ticks and no asterisks. If a tool has a feature, the table says it has it. Where a row would need a paragraph to be true, it is a paragraph somewhere else on this page instead of a row here.
| OpenAPI Generator | Voxgig | |
|---|---|---|
| License | Apache 2.0 | MIT |
| Account needed | No | No |
| Language targets | 40+ client generators, 20+ server frameworks | 23 language targets, 20 bundled plus Dart, Haskell and Lean from the langpack |
| Non-SDK output | Server stubs, docs, Postman, Protobuf, GraphQL, build config | CLI, MCP Server, Agent Skills, REPL, Semantic Model, and documentation editions through docgen |
| Cross-cutting behavior | Per generator, and uneven. Some have retry, most do not | 20 features, same options and behavior in every target |
| Customization | Mustache template overrides, then a Java fork | Model, templates, components, features, targets, packages |
| Runtime | JVM or Docker | Node |
| Regenerating over your edits | Overwrite | Three-way diff-merge, plus a doctor command |
| Behind it | A large volunteer community and a technical committee | One small company, trading since 2018 |
Lob publishes an SDK made with OpenAPI Generator from a version of its definition years older than today's. Voxgig built one from the current version, and both were run against a mock of the current version on the same four steps: list, load, create, and remove. The version gap explains Lob's lower operation count, so read that row as a measure of the input rather than of either generator. Voxgig's features are in the build and stay off until a client switches them on; the rows describe them switched on. Last measured 29 September 2026.
OpenAPI Generator
@lob/lob-typescript-sdk 1.4.2The TypeScript SDK Lob publishes on npm, generated with OpenAPI Generator 5.3.0 from an older version of the same definition.
Voxgig
voxgig-sdk/lob-sdkBuilt on 29 September 2026 from the current version of the same definition: eight targets from one run. A repository to build from, not a published package.
The definition: Lob's own OpenAPI definition, dist/lob-api-bundled.yml in lob/lob-openapi at commit ff3a7f5: OpenAPI 3.0.3, 58 paths, 105 operations, MIT. Its source.
| OpenAPI Generator | Voxgig | |
|---|---|---|
| Operations callable | 70 methods, from a years-older version of the definition | 105 of 105 |
| Mock scenario on addresses | 4 of 4 steps right | 4 of 4 right, with the key sent as Lob documents it: the username, with a blank password |
| Retries | None | On 408, 425, 429, 500, 502, 503 and 504, honoring Retry-After |
| Timeouts | No SDK option. Axios's own timeout passes through | 30 seconds per attempt by default |
| Pagination | Page tokens on list results, and you call list again yourself | Page and cursor state carried between calls in ctrl.paging, with no iterator |
| Idempotency keys | An optional argument on some create methods, which you supply | Generated for every mutating call, and kept across its retries |
| Rate limits | None | A client-side token bucket, and Retry-After honored on 429 |
| Logging | None | Request and response logging, with auth headers redacted |
| Offline test mode | None | A mock transport seeded with your data, which the generated tests run on |
| Metrics | None | Per-operation counts and timings, with no OpenTelemetry |
| Cancellation | No SDK option. An axios signal passes through | A signal stops stream() between items. Only the timeout aborts a request in flight |
| Hooks | Pass your own axios instance, with its interceptors | Custom features that hook every stage of a call |
| Errors | The raw AxiosError, rethrown with Lob's message copied in | One error class per SDK, carrying the HTTP status and a notFound flag |
| OpenAPI Generator | Voxgig | |
|---|---|---|
| Package | @lob/lob-typescript-sdk on npm | Not published. You build it from the repository |
| TypeScript package size | 3.54 MB in 245 files | 2.70 MB in 376 files |
| Runtime dependencies | 2: axios and tslib | None |
| Languages from this build | TypeScript | TypeScript, Python, PHP, Go, Ruby and Lua, plus a Go CLI and a Go MCP server |
| Shape | A class per API tag, such as AddressesApi, with a method per operation | 33 entities, such as Address, each with the list, load, create, update and remove operations the API has |
| Types | A model class per schema, for requests and responses | An interface per entity, from the response schema, with nested objects typed any |
| Tests | Not run here: the comparison used the published package | 455 generated TypeScript tests pass, as do the generated Go, Python, Ruby, Lua, and PHP suites |
The same calls in each, in TypeScript. Both samples type-check under strict mode against the SDK they name.
import { AddressEditable, AddressesApi, Configuration } from '@lob/lob-typescript-sdk'
const addresses = new AddressesApi(new Configuration({ username: process.env.LOB_API_KEY }))
const page = await addresses.list(10)
const address = await addresses.get('adr_123')
const created = await addresses.create(new AddressEditable({
name: 'Thing T. Thing',
address_line1: '1313 CEMETERY LN',
address_city: 'WESTFIELD',
address_state: 'NJ',
address_zip: '07090',
}))
await addresses.delete('adr_123')import { LobSDK } from '@voxgig-sdk/lob-sdk'
const client = new LobSDK({ apikey: process.env.LOB_APIKEY, secret: process.env.LOB_SECRET })
const addresses = await client.Address().list()
const address = await client.Address().load({ id: 'adr_123' })
const created = await client.Address().create({
name: 'Thing T. Thing',
address_line1: '1313 CEMETERY LN',
address_city: 'WESTFIELD',
address_state: 'NJ',
address_zip: '07090',
})
await client.Address().remove({ id: 'adr_123' })body until 8.18.0, although Lob puts it at body.data inside an allOf, so list returned nothing and the Address type carried the page's count and next_url. On 8.22.0 the list and the type both read the address.Idempotency-Key on nine creates. sdkgen sent it in the request body until 4.32.0, which sends every header parameter as a header, and Voxgig's idempotency feature can also generate the key for you.any (voxgig/sdkgen#220).doctor reports the drift either way.Corrections go to info@voxgig.com or an issue on the generator repository. A correction changes the page and moves its checked date; corrections from OpenAPI Generator's own team carry the most weight.
First-party sources for the claims on this page. Where they disagree with it, they are the authority.
The generator is MIT and open, and the catalog holds 600+ generated SDKs readable without installing anything.