Is the Network Information API supported everywhere?

Chrome, Edge, and Chromium-based browsers expose navigator.connection. Safari and Firefox do not — they will show "unsupported" rather than fake values.

How accurate is effectiveType?

It is a coarse classification (slow-2g, 2g, 3g, 4g) inferred from recent RTT and downlink — useful for adaptive loading, not for measuring actual bandwidth.

What does saveData mean?

The user has enabled a data-saver mode (Chrome Lite, Android Data Saver). Honor it by skipping background prefetches and large images.

Is anything transmitted by the tool?

No. The tool only reads from the browser API; nothing is sent over the network.

navigator.connection · live · effective type · local

Live network info readout

See your connection's effective type, downlink, RTT, and online status — straight from the Network Information API. Updates live as your network changes.

Network Info

Online

—

navigator.onLine

Type

—

effective

Downlink

—

current

RTT

—

round-trip

input · status

Network status

—

output · readings

Quick Start

How network info works

Browsers expose a NetworkInformation interface via navigator.connection. effectiveType maps your real link onto 4g / 3g / 2g / slow-2g buckets.

01
Read effective type
Coarse but useful classification for adaptive loading.
Inputs are treated as UTF-8 throughout the pipeline and validated client-side as you type — nothing dispatches until the value is well-formed.
apiinpututf-8client-sidevalidated
type · text4g · set
```
effectiveType
```
loaded · parsedclient-side
02
Check downlink
Estimated bandwidth in Mbps.
Each toggle re-computes through a memoised hook, so flipping options never resets your input and the UI stays snappy on large inputs.
bwoptionslivememoisedtoggles
downlink · memoisedMbps · live
```
10 Mbps
```
options set · memoisedlive
03
Observe RTT
Round-trip time estimate in milliseconds.
Randomness — where used — comes from crypto.getRandomValues, never Math.random. Heavy work sits in useMemo.
latcomputeinstantlocaldeterministic
rtt · instantms · computed
```
50 ms
```
computed · instantinstant
04
Adapt
Use these signals to defer heavy media on slow links.
Copy writes through navigator.clipboard and downloads use a Blob — zero network traffic. Same input plus same options always yield the same bytes.
adaptivecopydownloadzero-networkreproducible
ok · copiedready · copied
```
Adapt UI
```
shipped · ready to shipsuccess

Pro tips

Pro tips for everyday utilities

Reach for crypto.getRandomValues

Cryptographically random for IDs, tokens, salts. Math.random is for animation and games, not security.

Sort IDs lexicographically

UUID v4 has no time ordering. Use ULID or UUID v7 if you need sorted IDs.

Mock data with seeds

Faker-style libraries can be seeded so tests are reproducible. Embed the seed in the fixture file.

Reference cards beat memory

Cheatsheets for Vim, Git, Docker, Linux signals are faster than man pages when you’re mid-flow.

Browser APIs vary

Touch events, gamepads, and clipboard differ across vendors. Feature-detect before use.

Persist in the right place

localStorage for user preferences, sessionStorage for transient state, IndexedDB for structured data.

Use Cases

When network info helps

Adaptive media, offline-first, debugging.

Adaptive media

Serve lower-quality images on slow-2g. Random values come from crypto.getRandomValues — cryptographically secure for tokens, salts, and session IDs. Math.random is deterministic enough for animations but predictable enough to be a security bug.

CSPRNG-backed

Offline-first PWAs

Sync queues when transitioning online. Pair with hashids, ULID, or UUID v7 when you need both random and sortable — useful for primary keys, public-facing IDs, and event log ordering without a sequence column.

reproducible

Save Data hints

Respect Save-Data user preference. Output is deterministic given the same seed, so fixtures and tests stay reproducible across CI runs and contributor machines. Embed the seed in the fixture file for full replay.

snappy

Connection debugging

Spot flaky RTT in a field bug report. Heavy work runs through useMemo so the UI stays snappy on large inputs. Same input + same options yields identical bytes — the kind of stability snapshot tests rely on.

feature-detected

Background sync

Pause uploads on metered links. Storage tools persist to the right backend: localStorage for user preferences, sessionStorage for transient state, IndexedDB for structured data. Pick the right shelf and quota worries disappear.

deterministic

Analytics

Tag events with network type. Browser feature detection: clipboard, fullscreen, gamepad, and Web Bluetooth APIs gracefully fall back when unavailable. No surprise white screens on Safari or older Firefox.

production-ready

FAQ

Frequently asked questions

Why are some fields '—'?

Safari and Firefox stable don't implement navigator.connection. Chromium-based browsers do.

What's effectiveType?

A bucket (4g, 3g, 2g, slow-2g) that maps measured RTT/downlink onto traditional cellular tiers.

Is downlink real-time?

Browsers throttle updates to ~10s and round values to avoid fingerprinting.

What about Save Data?

If the user opts into Save Data, saveData becomes 'on' — respect it by deferring large assets.

Is anything sent to a server?

No. Readings come from the browser API and stay local.

Suggest a tool

Something missing?

Tell us what you need. We ship the top requests every two weeks.

47 in queue·8 shipped this month

Request queued. Thanks!