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Browser Extensions · head to head

FireMonkey vs Ory Kratos

FireMonkey logo

FireMonkey

Browser Extensions

User scripts and user styles in one Firefox extension

From
Free
Rated
-
Full reviewWebsite
Ory Kratos logo

Ory Kratos

Cybersecurity

Headless identity and user management API

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: FireMonkey firefox only, and requires a recent one: version 93 on desktop, 113 on Android.; Ory Kratos headless means you build every screen, which is significant work compared with a hosted login page
  • They diverge on capability: FireMonkey covers Scripts and styles together, Ory Kratos covers Headless API.
  • Prices and features above were last checked on 15 September 2026.

Where they differ

Only the attributes on which FireMonkey and Ory Kratos actually diverge.

Attributes where FireMonkey and Ory Kratos differ
AttributeFireMonkeyOry Kratos
Pricing modelopen-sourceOpen-source self-hosted, with a paid managed network
PlatformsFirefoxLinux, Docker, Kubernetes, Self-hosted
CategoryBrowser ExtensionsCybersecurity

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 FireMonkey

  • Scripts and styles together
  • Monaco editor with ESLint
  • Unlimited client-side storage
  • Global injection
  • Notifications and clipboard
  • Firefox for Android

Only in Ory Kratos

  • Headless API
  • Self-service flows
  • Multi-factor authentication
  • Pluggable identity schemas

What people use each for

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

FireMonkey

  • Running user scripts and user styles without two separate extensionsnot Ory Kratos
  • Restyling sites with CSS alongside scripted behaviour changesnot Ory Kratos
  • Editing scripts in a full editor inside the browsernot Ory Kratos
  • Injecting CSS globally across every sitenot Ory Kratos
  • Managing a mixed library of scripts and styles from one dashboardnot Ory Kratos

Ory Kratos

  • Products needing complete control over the look and flow of authenticationnot FireMonkey
  • Applications that must not hand user identity data to a third partynot FireMonkey
  • Teams building identity as infrastructure across several servicesnot FireMonkey

Where each one falls short

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

FireMonkey

  • Firefox only, and requires a recent one: version 93 on desktop, 113 on Android.
  • Not a drop-in replacement for Greasemonkey, Tampermonkey or Stylus. The project says so itself, so an existing library may need adjusting.
  • A much smaller user base than Tampermonkey or Violentmonkey, which means fewer people have hit the bug you are about to hit.
  • No Chrome, Edge or Safari build, so it cannot be the answer for anyone working across browsers.
  • Combining scripts and styles in one extension also combines the blast radius: one extension with permission to inject both into every page.

Ory Kratos

  • Headless means you build every screen, which is significant work compared with a hosted login page
  • More moving parts than a monolithic IAM: Kratos handles identity, and OAuth2 needs Ory Hydra alongside
  • Documentation assumes real familiarity with identity concepts and is not a gentle introduction
  • Self-hosting identity carries the security and availability burden that hosted providers absorb

Pricing, plan by plan

FireMonkey

Free
  • Open sourceFree
    • MPL-2.0 licensed
    • Unlimited scripts and styles
    • No account required

Ory Kratos

Free
  • Self-hostedFree
    • Full identity server
    • All flows
    • Community support

Which should you pick?

Choose FireMonkey if

  • You need scripts and styles together.
  • You want to start without paying.
  • You work on Firefox.
  • You also want monaco editor with eslint.
FireMonkey review

Choose Ory Kratos if

  • You need headless api.
  • You want to start without paying.
  • You work on Linux, Docker, Kubernetes, Self-hosted.
  • You also want self-service flows.
Ory Kratos review

Questions people ask

Is FireMonkey or Ory Kratos better?
Neither clearly leads. FireMonkey starts at Free and Ory Kratos at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, FireMonkey or Ory Kratos?
FireMonkey starts at Free and Ory Kratos at Free.
Does FireMonkey or Ory Kratos run on more platforms?
FireMonkey runs on Firefox. Ory Kratos runs on Linux, Docker, Kubernetes, Self-hosted.
Can I use FireMonkey for free?
Both have a free tier, so you can try either at no cost before committing.
What is FireMonkey best used for?
FireMonkey is most often used for running user scripts and user styles without two separate extensions, restyling sites with css alongside scripted behaviour changes, editing scripts in a full editor inside the browser, injecting css globally across every site. Of those, running user scripts and user styles without two separate extensions and restyling sites with css alongside scripted behaviour changes are not what Ory Kratos is typically brought in for.
What can FireMonkey do that Ory Kratos cannot?
FireMonkey covers Scripts and styles together, Monaco editor with ESLint, Unlimited client-side storage, Global injection. Ory Kratos covers Headless API, Self-service flows, Multi-factor authentication, Pluggable identity schemas.

Answered from the vendors’ own pages

FireMonkey: What makes FireMonkey different from Violentmonkey?

It manages user styles as well as user scripts. The usual arrangement is a script manager plus a separate style manager such as Stylus; FireMonkey replaces both with one extension.

Source
Ory Kratos: Is Ory Kratos free?

Yes, open source and free to self-host. Ory Network is a paid managed service.

FireMonkey: Which browsers does FireMonkey support?

Firefox only. Desktop requires Firefox 93 or later and Android requires 113, with an API minimum of 102.

Source
Ory Kratos: What does headless mean here?

Kratos provides identity flows as APIs and no user interface. You build the login, registration and recovery screens yourself.

FireMonkey: Is FireMonkey open source?

Yes, under the MPL-2.0 licence.

Source
Ory Kratos: Does Kratos do OAuth2?

No. Kratos handles user identity; OAuth2 and OpenID Connect provider functionality is Ory Hydra, a separate component.

FireMonkey: Will my existing Tampermonkey scripts work?

Not necessarily. The project states that while it shares functionality with Greasemonkey, Tampermonkey and Stylus, there are differences, so scripts and styles written for those may need adjusting.

Source
FireMonkey: What editor does FireMonkey use?

Current versions use the Monaco editor with ESLint, the same editor component that powers VS Code.

Source
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