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Developer Tools · head to head

GNAT Pro vs Sphinx

GNAT Pro logo

GNAT Pro

Developer Tools

Software development environments and toolchains for Ada, C/C++ and Rust

From
On request
Rated
-
Full reviewWebsite
Sphinx logo

Sphinx

Documentation

Documentation generator built for large technical projects

From
Free
Rated
-
Full reviewWebsite

The short version

  • Only Sphinx has a free tier, so it costs nothing to try first.
  • Each has a real cost: GNAT Pro no pricing published on website; requires contacting AdaCore directly for quotes; Sphinx reStructuredText is harder to write than Markdown and puts off contributors, though MyST now allows Markdown

Where they differ

Only the attributes on which GNAT Pro and Sphinx actually diverge.

Attributes where GNAT Pro and Sphinx differ
AttributeGNAT ProSphinx
Starting priceOn requestFree
Pricing modelquoteOpen source, no licence fee
Free tierNoYes
PlatformsWebLinux, macOS, Windows
CategoryDeveloper ToolsDocumentation

Identical on both: 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 GNAT Pro

Nothing recorded that Sphinx does not also cover.

Only in Sphinx

  • Cross-references
  • API autodoc
  • Multi-format output
  • Extension ecosystem

What people use each for

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

GNAT Pro

  • Building certified avionics software meeting DO-178B/C standardsnot Sphinx
  • Developing automotive embedded systems with ISO-26262 compliancenot Sphinx
  • Integrating Ada, C/C++, and Rust components in single codebasenot Sphinx
  • Managing software supply chain vulnerabilities and SBOMsnot Sphinx
  • Supporting long-lived software systems spanning decadesnot Sphinx

Sphinx

  • Large technical documentation needing reliable cross-referencesnot GNAT Pro
  • Python projects generating API docs from docstringsnot GNAT Pro
  • Documentation that must ship as PDF as well as HTMLnot GNAT Pro

Where each one falls short

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

GNAT Pro

  • No pricing published on website; requires contacting AdaCore directly for quotes
  • Vendor indicates per-user, per-year subscription model but does not disclose specific costs

Sphinx

  • reStructuredText is harder to write than Markdown and puts off contributors, though MyST now allows Markdown
  • Configuration is complex and the default output is dated-looking without theme work
  • Build times on large documentation sets are slow
  • Heavier than the problem for a small project that only needs a few pages

Pricing, plan by plan

GNAT Pro

On request

No published plan breakdown. See the GNAT Pro review.

Sphinx

Free
  • SphinxFree
    • Full functionality
    • Commercial use permitted
    • Community support

Which should you pick?

Choose GNAT Pro if

Nothing in the data separates GNAT Pro from Sphinx on the points above - pick on price and on how each one feels to use.

GNAT Pro review

Choose Sphinx if

  • You need cross-references.
  • You want to start without paying.
  • You work on Linux, macOS, Windows.
  • You also want api autodoc.
Sphinx review

Questions people ask

Is GNAT Pro or Sphinx better?
Neither clearly leads. GNAT Pro starts at On request and Sphinx at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, GNAT Pro or Sphinx?
Sphinx has a free tier; the other does not. Paid plans start at On request for GNAT Pro and Free for Sphinx.
Does GNAT Pro or Sphinx run on more platforms?
GNAT Pro runs on Web. Sphinx runs on Linux, macOS, Windows.
Can I use Sphinx for free?
Yes. Sphinx has a free tier, so you can try it without paying. GNAT Pro starts at On request.
What is GNAT Pro best used for?
GNAT Pro is most often used for building certified avionics software meeting do-178b/c standards, developing automotive embedded systems with iso-26262 compliance, integrating ada, c/c++, and rust components in single codebase, managing software supply chain vulnerabilities and sboms. Of those, building certified avionics software meeting do-178b/c standards and developing automotive embedded systems with iso-26262 compliance are not what Sphinx is typically brought in for.
What can GNAT Pro do that Sphinx cannot?
Sphinx covers Cross-references, API autodoc, Multi-format output, Extension ecosystem.

Answered from the vendors’ own pages

GNAT Pro: How much does GNAT Pro cost?

GNAT Pro pricing is not published on the website. Customers must request a pricing quote by contacting AdaCore directly or speaking with a GNAT Pro expert.

Source
Sphinx: Is Sphinx free?

Yes, open source under the BSD licence.

GNAT Pro: What is GNAT Pro licensing model?

GNAT Pro is sold on a per-user, per-year basis with no license locks. Customers can request pricing for their specific needs.

Source
Sphinx: Do I have to write reStructuredText?

Not any more. The MyST extension allows Markdown, though reStructuredText remains the native format and most examples use it.

Sphinx: Why do large projects choose Sphinx?

Automatic cross-referencing and API extraction from docstrings, which lighter generators do not provide.

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