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Documentation · head to head

Doxygen vs Kong Gateway

Doxygen logo

Doxygen

Documentation

Free, open source documentation generator that builds reference docs from source code comments

From
Free
Rated
-
Full reviewWebsite
Kong Gateway logo

Kong Gateway

APIs

Open-source and cloud API gateway for managing microservices traffic

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Doxygen there is no vendor or paid support contract; when something breaks in a large or unusual codebase, the only recourse is community mailing lists, forums or reading the source; Kong Gateway the free open-source gateway lacks the analytics, portals, and support of the paid Konnect tiers.
  • They diverge on capability: Doxygen covers Code comment parsing, Kong Gateway covers API request routing.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Doxygen and Kong Gateway actually diverge.

Attributes where Doxygen and Kong Gateway differ
AttributeDoxygenKong Gateway
Pricing modelOpen source, no licence feefreemium
PlatformsLinux, macOS, Windowsweb, linux, api
CategoryDocumentationAPIs
FoundedUnknown2017

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Doxygen

  • Code comment parsing
  • Multi-format output
  • Call and inheritance graphs
  • Markdown support
  • CI-friendly build

Only in Kong Gateway

  • API request routing
  • Plugin ecosystem
  • Developer portals
  • AI Gateway
  • Analytics and observability
  • SSO and audit logs

What people use each for

The jobs each tool is most often brought in to do.

Doxygen

  • An engineering team generating API reference documentation directly from source code comments as part of a CI buildnot Kong Gateway
  • A library or SDK maintainer who wants reference docs that cannot drift out of sync with the code because they are generated from itnot Kong Gateway
  • An internal platform team documenting a large C++ or Java codebase where structure like class hierarchies and call graphs matters more than prosenot Kong Gateway
  • A project with no documentation budget that still needs professional-looking reference output without any licence costnot Kong Gateway

Kong Gateway

  • Routing and securing traffic across microservicesnot Doxygen
  • Publishing internal or external developer portalsnot Doxygen
  • Managing rate limits and authentication at the API edgenot Doxygen
  • Gateway-level routing to multiple LLM providersnot Doxygen

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Doxygen

  • There is no vendor or paid support contract; when something breaks in a large or unusual codebase, the only recourse is community mailing lists, forums or reading the source
  • Default HTML output looks dated and requires a third-party theme such as Doxygen Awesome to look acceptable to a modern audience, which is extra setup work not included
  • It only generates reference documentation from code comments; it is not a narrative documentation tool, help centre or CCMS, so most teams need a separate tool for guides and tutorials
  • Comment syntax and configuration have a real learning curve, and inconsistent comment discipline across a team produces inconsistent or sparse output regardless of the tool
  • Multi-language support varies in depth; parsing quality for languages outside its C-family core (C++, C, C#, Objective-C) is generally weaker than for its primary targets
  • There is no built-in hosting, search analytics, or reader-facing help centre features, so publishing the generated docs anywhere usable still requires separate infrastructure

Kong Gateway

  • The free open-source gateway lacks the analytics, portals, and support of the paid Konnect tiers.
  • Plus tier caps API requests at 1M/month before incurring per-million overage charges.
  • Enterprise pricing is custom and not published, making budgeting harder without sales contact.
  • Configuration and plugin management can require significant operational expertise to run at scale.

Pricing, plan by plan

Doxygen

Free
  • DoxygenFree
    • Full functionality
    • No usage limits
    • Community mailing list and GitHub issue support

Kong Gateway

Free
  • Free TrialFree
    • 30-day enterprise functionality trial
    • Unlimited gateways
    • 30-day analytics retention
  • Plus$undefined/month
    • Up to 5 serverless, 2 hybrid, 2 dedicated cloud gateways
    • 1M API requests/month included
    • Up to 2 developer portals
  • Enterprise$undefined/month
    • Unlimited hybrid and dedicated cloud gateways
    • Unlimited developer portals
    • SSO and audit logs

Which should you pick?

Choose Doxygen if

  • You need code comment parsing.
  • You want to start without paying.
  • You work on Linux, macOS, Windows.
  • You also want multi-format output.
Doxygen review

Choose Kong Gateway if

  • You need api request routing.
  • You want to start without paying.
  • You work on web, linux, api.
  • You also want plugin ecosystem.
Kong Gateway review

Questions people ask

Is Doxygen or Kong Gateway better?
Neither clearly leads. Doxygen starts at Free and Kong Gateway at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Doxygen or Kong Gateway?
Doxygen starts at Free and Kong Gateway at Free.
Does Doxygen or Kong Gateway run on more platforms?
Doxygen runs on Linux, macOS, Windows. Kong Gateway runs on web, linux, api.
Can I use Doxygen for free?
Both have a free tier, so you can try either at no cost before committing.
What is Doxygen best used for?
Doxygen is most often used for an engineering team generating api reference documentation directly from source code comments as part of a ci build, a library or sdk maintainer who wants reference docs that cannot drift out of sync with the code because they are generated from it, an internal platform team documenting a large c++ or java codebase where structure like class hierarchies and call graphs matters more than prose, a project with no documentation budget that still needs professional-looking reference output without any licence cost. Of those, an engineering team generating api reference documentation directly from source code comments as part of a ci build and a library or sdk maintainer who wants reference docs that cannot drift out of sync with the code because they are generated from it are not what Kong Gateway is typically brought in for.
What can Doxygen do that Kong Gateway cannot?
Doxygen covers Code comment parsing, Multi-format output, Call and inheritance graphs, Markdown support. Kong Gateway covers API request routing, Plugin ecosystem, Developer portals, AI Gateway.

Answered from the vendors’ own pages

Doxygen: Is Doxygen really free with no paid tier?

Yes, it is GPL-licensed open source software with no company selling licences or support contracts.

Kong Gateway: Is Kong Gateway free?

Kong's core gateway is open source and free to self-host. Kong Konnect, the managed cloud platform, offers a 30-day free trial before moving to paid Plus or custom Enterprise pricing.

Source
Doxygen: Does Doxygen write documentation for me?

No, it extracts and formats documentation from comments a developer has already written in the source code; it does not generate prose from uncommented code.

Kong Gateway: How is usage metered on the Plus plan?

The Plus plan includes 1M API requests per month, with additional usage billed at $200 per extra 1 million requests up to a 10M/month cap, plus per-gateway and per-LLM-model charges.

Source
Doxygen: Can it produce anything besides reference documentation?

It can render standalone markdown pages alongside the generated reference content, but it is not a general authoring or publishing platform.

Kong Gateway: What support is included?

Plus includes email support with a 2-business-day SLA, while Enterprise adds dedicated success managers and professional services.

Source
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