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Developer Tools · head to head

Deno vs Mozilla Firefox

Deno logo

Deno

Developer Tools

A fast, open-source, fully Node-compatible JS runtime with TypeScript baked right in

From
Free
Free plan
Yes
Full reviewWebsite
Mozilla Firefox logo

Mozilla Firefox

Technology

An independent web browser with its own rendering engine, funded almost entirely by search placement deals.

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: Deno egress bandwidth overage costs $0.20/GB which can become expensive for high-traffic applications; Mozilla Firefox roughly 85 per cent of Mozilla's revenue comes from search default placement deals, overwhelmingly with Google, so the organisation that competes with Chrome depends on Chrome's owner for its funding and any renegotiation lands on Firefox's engineering budget within a quarter.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Deno and Mozilla Firefox actually diverge.

Attributes where Deno and Mozilla Firefox differ
AttributeDenoMozilla Firefox
Pricing modelfreemiumUnknown
PlatformsWebWindows, macOS, Linux, iOS, Android
CategoryDeveloper ToolsTechnology
FoundedUnknown2004

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 Deno

Nothing recorded that Mozilla Firefox does not also cover.

Only in Mozilla Firefox

  • Gecko engine
  • Full webRequest blocking
  • Total Cookie Protection
  • Container tabs
  • Extended Support Release
  • policies.json and ADMX
  • Built-in developer tools
  • Firefox Sync

What people use each for

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

Deno

  • Running TypeScript natively without transpilation overheadnot Mozilla Firefox
  • Migrating Node.js applications to secure-by-default runtimenot Mozilla Firefox
  • Deploying edge functions and serverless containers seamlesslynot Mozilla Firefox
  • Consolidating developer tools into single binarynot Mozilla Firefox

Mozilla Firefox

  • Web development where you need to test against a non-Chromium engine before shipping, because Chromium-only testing hides real bugsnot Deno
  • Users who require a full-strength content blocker, which Chrome's Manifest V3 no longer permitsnot Deno
  • Managed fleets that need a browser on a slow release cadence with Group Policy control, using the ESR channelnot Deno
  • Handling several accounts on the same service at once through container tabs, without separate profiles or private windowsnot Deno

Where each one falls short

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

Deno

  • Egress bandwidth overage costs $0.20/GB which can become expensive for high-traffic applications
  • CPU time overage is $0.10/hour on Pro and Builder tiers, adding to costs for compute-intensive workloads
  • Enterprise pricing is not disclosed; requires sales contact

Mozilla Firefox

  • Roughly 85 per cent of Mozilla's revenue comes from search default placement deals, overwhelmingly with Google, so the organisation that competes with Chrome depends on Chrome's owner for its funding and any renegotiation lands on Firefox's engineering budget within a quarter.
  • Desktop market share sits at a few per cent, so commercial sites are tested against Chrome and Safari and a Firefox-only rendering or WebRTC bug is triaged as low priority by the site owner, leaving you with the workaround.
  • On iOS and iPadOS the browser is a WebKit shell required by Apple's rules, so it delivers the interface and Sync but none of the engine, extension or tracking-protection behaviour that make Firefox worth choosing on desktop.
  • Mozilla declines to implement several hardware-facing APIs on principle, including WebUSB, WebSerial, Web Bluetooth and WebHID, so a web application that talks to a device simply does not run and no configuration flag changes that.
  • Enterprise management is limited to policies.json and ADMX templates; there is no first-party equivalent of Chrome Browser Cloud Management, so fleet-wide reporting on versions and extensions requires third-party tooling you have to buy or build.
  • Mozilla repeatedly ships decisions its own user base objects to, such as enabling Privacy Preserving Attribution by default and the 2025 Terms of Use rewrite, and reversals arrive after the news cycle, so deploying it on a privacy argument means owning the communications work each time.

Pricing, plan by plan

Deno

Free
  • FreeFree
    • 1 million requests/month
    • 20GB egress bandwidth
    • 10 apps
  • Pro$20/month
    • 5 million requests/month
    • 200GB egress
    • 50 apps
  • Builder$200/month
    • 25 million requests/month
    • 2,000GB egress
    • 10,000 apps
  • Enterprise$null/month
    • Custom limits on all metrics
    • 99.95% reliability SLA
    • Email support with SLA

Mozilla Firefox

Free

No published plan breakdown. See the Mozilla Firefox review.

Which should you pick?

Choose Deno if

  • You want to start without paying.
Deno review

Choose Mozilla Firefox if

  • You need gecko engine.
  • You want to start without paying.
  • You work on Windows, macOS, Linux, iOS, Android.
  • You also want full webrequest blocking.
Mozilla Firefox review

Questions people ask

Is Deno or Mozilla Firefox better?
Neither clearly leads. Deno starts at Free and Mozilla Firefox at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Deno or Mozilla Firefox?
Deno starts at Free and Mozilla Firefox at Free.
Does Deno or Mozilla Firefox run on more platforms?
Deno runs on Web. Mozilla Firefox runs on Windows, macOS, Linux, iOS, Android.
Can I use Deno for free?
Both have a free tier, so you can try either at no cost before committing.
What is Deno best used for?
Deno is most often used for running typescript natively without transpilation overhead, migrating node.js applications to secure-by-default runtime, deploying edge functions and serverless containers seamlessly, consolidating developer tools into single binary. Of those, running typescript natively without transpilation overhead and migrating node.js applications to secure-by-default runtime are not what Mozilla Firefox is typically brought in for.
What can Deno do that Mozilla Firefox cannot?
Mozilla Firefox covers Gecko engine, Full webRequest blocking, Total Cookie Protection, Container tabs.

Answered from the vendors’ own pages

Deno: How much does Deno Deploy cost?

Deno Deploy offers a free tier at $0/month, Pro at $20/month, and Builder at $200/month. Enterprise has custom pricing. All plans include base request and bandwidth limits, with overage charges for additional usage.

Source
Mozilla Firefox: Does uBlock Origin still work on Firefox?

Yes. Firefox has kept the blocking webRequest API that Chrome removed with Manifest V3, so uBlock Origin runs with its full rule set rather than the cut-down Lite version Chrome requires.

Deno: What are Deno Deploy's overage charges?

Egress bandwidth overages cost $0.20 per GB. CPU time overages are $0.10 per hour on Pro and Builder tiers. Memory time and KV database operations also incur charges beyond included limits.

Source
Mozilla Firefox: Is Firefox on iPhone the same browser?

No. Apple's platform rules require it to use WebKit, so on iOS and iPadOS you get Firefox's interface, Sync and bookmarks on top of Safari's engine. The privacy and extension behaviour are not the same.

Deno: How many apps can I deploy on Deno's free plan?

The free tier includes 10 apps with up to 1 concurrent build. Pro tier supports 50 apps with 3 concurrent builds, and Builder supports 10,000 apps with 20 concurrent builds.

Source
Mozilla Firefox: How is Mozilla funded, and does that matter?

Mainly by payments for making a search engine the default, with Google as the dominant payer. It matters because it is a single-source dependency on a direct competitor, and it has been the subject of antitrust litigation whose outcome Mozilla does not control.

Deno: How many team members can access Deno Deploy?

The free tier supports up to 3 team members. Pro supports 10 team members. Builder supports 25 team members. Enterprise has custom seat limits.

Source
Mozilla Firefox: Can I manage it across a company fleet?

Yes, through policies.json or Windows Group Policy with the ADMX templates, and the ESR channel gives you a roughly yearly major version instead of four-weekly. There is no first-party cloud management console, so reporting needs other tooling.

Mozilla Firefox: Will every site work in it?

Most will. The exceptions cluster around sites tested only in Chrome, legacy enterprise applications, and anything using WebUSB, WebSerial, Web Bluetooth or WebHID, which Firefox does not implement at all.

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