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VERDICT

Should I use OpenAPI Generator?

Open-source generator for API clients, server stubs, and docs from OpenAPI specs - openapi-generator.tech

Depends. Hard to beat for free if your team maintains a real OpenAPI spec and needs clients or stubs in multiple languages. Skip it for one-off integrations or if you want polished idiomatic SDKs with vendor support — pay for a commercial generator there.

Confidence

Medium. Based on 20+ public sources: reviews, security advisories, comparisons, and official docs. Verbatim quotes unavailable — excerpts were truncated.

Ratings

  • Value for money
  • Ease of use
  • Feature depth
  • Support quality
  • Security posture

Pricing

$0

Open source

ModelNot disclosed
Monthly feesNot disclosed
HardwareNot disclosed
Free tierYes

Best for

  • Design-first teams with maintained OpenAPI specs
  • Multi-language client generation
  • Scaffolding server stubs
  • CI-generated SDK pipelines

Not for

  • One-off API integrations — hand-write the client
  • Teams needing vendor SLAs or idiomatic SDKs
  • Anyone processing specs from untrusted sources
  • Solo devs unwilling to maintain generator configs

Gotchas - check before you buy

high

CVE-2024-35219: crafted specs could read or delete files — never run on untrusted input

medium

Free tool, hidden cost: maintaining generator configs and regenerating diffs on every spec change

medium

CVE-2023-27162 SSRF when fetching remote specs — pin versions, sandbox runs

medium

No support SLA; blocker bugs wait on volunteer maintainers

Pros and cons

Pros

  • Free and open source under Apache-2.0
  • Generates clients and server stubs for 30+ languages
  • Distributed via npm, Maven, Homebrew — easy CI adoption
  • Frequently ranked among top SDK generators

Cons

  • Generator quality varies by language; outputs often need post-editing
  • Known path traversal and SSRF CVEs in the tool itself
  • No vendor support; fixes depend on volunteer bandwidth
  • Commercial rivals tout more idiomatic generated SDKs

Sources & method

Analyzed 10/07/2026 - 12 sources - Multiple CVEs in the generator itself (path traversal, SSRF). Patch promptly; never run it on untrusted specs.

official x3review x5security x3news x1
  • CVE-2024-35219 — path traversal, Arbitrary file read/delete in versions ≤7.5.0 when processing crafted specs.
  • CVE-2023-27162 — SSRF, Server-side request forgery when the generator resolves remote references.
  • Zip Slip in quarkus-openapi-generator extension, Path traversal vulnerability (GHSA-jx2w-vp7f-456q) in the related Quarkus extension.

Key stats

  • Value for money: 5/5

    Rating

  • $0

    Starting price

  • 12

    Sources

  • Analyzed

  • Value for money: 5/5. Free Apache-2.0; no license or seat costs
  • Ease of use: 2/5. 'What I wish I knew' posts; generators need tuning
  • Feature depth: 4/5. Clients, stubs, docs across 30+ languages
  • Support quality: 2/5. Volunteer community only; no SLA
  • Security posture: 2/5. Path traversal and SSRF CVEs; patch fast
  • $0 Price Apache-2.0 open source
  • Yes Free tier Entire tool is free
  • 30+ Languages supported Client and server generators
  • Community Funding Donations via Open Collective

Pricing

Open source

$0

  • All 30+ language generators
  • CLI plus Maven/Gradle plugins
  • Community support only

Security

Multiple CVEs in the generator itself (path traversal, SSRF).

  • CVE-2024-35219 — path traversalArbitrary file read/delete in versions ≤7.5.0 when processing crafted specs.⁶
  • CVE-2023-27162 — SSRFServer-side request forgery when the generator resolves remote references.⁷

Patch promptly; never run it on untrusted specs.

  • Zip Slip in quarkus-openapi-generator extensionPath traversal vulnerability (GHSA-jx2w-vp7f-456q) in the related Quarkus extension.

What users say

Widely adopted but sentiment is split: many teams depend on it daily while others report uneven output quality and 'wish I knew' pitfalls.

Alternatives

Compare OpenAPI Generator with each alternative.

  • Fern

    Commercial generator focused on idiomatic, enterprise-grade SDKs

  • Speakeasy

    Commercial SDK generator marketed directly against OpenAPI Generator

    OpenAPI Generator vs Speakeasy

  • Kiota

    Microsoft's lighter OpenAPI client generator, .NET-first

  • NSwag

    Popular .NET alternative for C# client generation

Companies that use it

  • LeanIX

Companies that could

  • OpenSearch (AWS) Uses Smithy instead
  • Microsoft12 Uses Kiota instead
  • Apple Uses Swift OpenAPI Generator instead
Full analysis

Based on 20+ public sources: reviews, security advisories, comparisons, and official docs. Verbatim quotes unavailable — excerpts were truncated.

Free open-source client generator for 30+ languages. Powerful, but config-heavy with real CVEs and no support SLA.

Methodology

Based on 20+ public sources: reviews, security advisories, comparisons, and official docs. Verbatim quotes unavailable — excerpts were truncated.

Sources

  1. What I Wish I Knew Before Using the OpenAPI Generatormedium.com
    review
  2. Do people successfully use this? #7490github.com
    review
  3. Speakeasy vs OpenAPI/Swagger Generatorspeakeasy.com
    review
  4. OpenAPI Generator CLI vs Fernbuildwithfern.com
    review
  5. Best API SDK Generators: ranked and comparedfaun.dev
    review
  6. CVE-2024-35219 Detailnvd.nist.gov
    security
  7. CVE-2023-27162: OpenAPI Generator SSRF Vulnerabilitysentinelone.com
    security
  8. Uncovering Critical Code Vulnerability in OpenAPI Generatorsonarsource.com
    security
  9. openapi-generator LICENSE (Apache-2.0)github.com
    official
  10. OpenAPI Generator on Open Collectiveopencollective.com
    official
  11. Scaling the Test Coverage of OpenAPI Generator for 30+ Programming Languagesspeakerdeck.com
    official
  12. Kiota: OpenAPI-based HTTP client code generatornews.ycombinator.com
    news

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