Network Class Identifier
Identify the network class (A/B/C/D/E) for an IPv4 address with default mask, host count, and private range detection.
How it works
- 1Enter your values in the fields above
- 2Click "Calculate" — all math runs in your browser
- 3View your results instantly
What to do next
About Network Class Identifier
Network Class Identifier is the kind of utility you bookmark and reach for when you need it. Identify the network class (A/B/C/D/E) for an IPv4 address with default mask, host count, and private range detection. It loads quickly, works on any modern browser, and produces a result you can download or copy in a single click.
From a technical standpoint, Network Class Identifier is JavaScript and standard browser APIs running in your tab. The browser is the runtime; the page is the interface. Maximum input size: 0 MB per run.
The execution path is auditable from the page itself: open developer tools, switch to the Network tab, run a job. The requests you see are static-asset GETs for the engine and the page resources. The actual work is JavaScript code running against the bytes already in your tab's memory.
The heaviest users of Network Class Identifier tend to be backend developers inspecting requests, devops engineers crafting one-liners and frontend developers prepping fixtures. Each group brings slightly different expectations to the tool, but the same single-page architecture serves every one of them with the same response time.
Network Class Identifier is shaped for the gap between "I'll do it by hand" and "I'll script it." When the job is small enough that automating it would take longer than doing it, but annoying enough to want a focused tool — that is the situation this page is built for.
On limits: 0 MB per file is the ceiling. Output formats and quality settings are listed in the controls panel above, and they apply to every run.
Network Class Identifier is intentionally narrow in what it does, which makes it easy to slot into a longer workflow. Take its output, hand it to whichever next tool fits the job, and Network Class Identifier stays out of your way until the next time you need it.
The transformation in Network Class Identifier is deterministic — the same input plus the same options produces the same result every run. That predictability matters when the result has to match an upstream specification or be reproducible later.
The output handed back by Network Class Identifier is the output file. If you would prefer to keep the result in the browser instead of downloading it, you can copy it from the result panel and paste it directly into another tab — useful when the next tool in your workflow expects pasted text rather than a file.
A short note on how Network Class Identifier came to look the way it does: every iteration started by watching how someone unfamiliar with the tool actually used it, then removing whatever got in their way. That is why the upload area dominates the screen, the run button is bigger than the secondary controls, and the result panel is unmissable when the job finishes.
Network Class Identifier produces deterministic output: the same input plus the same options always produces the same result. That predictability matters when the result has to match an upstream specification or be reproducible later.
A few practical tips that experienced users of Network Class Identifier pick up over time. First, keep your default browser updated — the engine relies on standard web APIs and newer browser versions are noticeably faster than ones from a few years ago. Second, close other heavy tabs before processing a large input; the engine shares CPU and memory with whatever else is open. Third, if you re-run the same kind of job often, your last-used settings are remembered for the rest of the tab session, so subsequent runs are essentially one click.
Common gotchas worth flagging: the supported formats are listed in the upload area. The 0 MB ceiling is per-file, not per-session; you can run as many separate jobs as you like, but a single oversized input will be rejected on load.
Open the workspace above to start using Network Class Identifier. The engine loads on the first interaction so the page itself stays light, and once the tool is warm it processes subsequent jobs quickly. The moment the page is interactive, the tool is ready to do real work on your file.
How it works
- 1Open the Network Class Identifier workspace above. The interface is a single page, so there is nothing to navigate.
- 2Select the developer file you want to process — drag-and-drop and the file picker both work.
- 3Adjust the options to match what you need. Sensible defaults cover the most common case, so you can usually skip this step.
- 4Hit the run button. standard browser APIs does the work in your browser tab.
- 5Save the output when it is ready.
- 6Repeat the process for additional inputs whenever you need to. The page stays loaded, so subsequent runs are quick.
Common use cases
- Decode a token to confirm its claims during a debugging session using Network Class Identifier.
- Hash a string for a quick reproducibility check.
- Generate a quick fixture without leaving the browser.
- Validate a config blob before pushing to staging.
- Pretty-print a minified blob during incident triage.
- Convert between data formats while wiring up an integration.
- Inspect a regex against a test string before committing it.
- Encode binary content for transport in a JSON body.
- Inspect a payload during local development without writing a script.
FAQ
What are network classes?
A classful addressing system: Class A (0-127), B (128-191), C (192-223), D (224-239 multicast), E (240-255 reserved).
Are classes still used?
Classful addressing is mostly replaced by CIDR, but classes are still relevant for understanding private ranges and default masks.
What is a private address?
RFC 1918 private ranges: 10.0.0.0/8 (Class A), 172.16.0.0/12 (Class B), 192.168.0.0/16 (Class C). Not routable on the public internet.
What is loopback?
127.0.0.0/8 addresses (typically 127.0.0.1) loop back to the same machine, used for testing.
What is APIPA/link-local?
169.254.x.x addresses auto-assigned when DHCP is unavailable. Only valid on the local network segment.
Private?
Yes — classification runs locally.
Does Network Class Identifier work with screen readers?
Network Class Identifier uses native HTML controls wherever possible, which means keyboard navigation, focus rings, and screen-reader labels work the way the platform expects. The drop zone accepts files via the keyboard-accessible file picker as well as drag-and-drop, and result downloads use standard browser download flows. If you spot an accessibility gap, Favtoo treats it as a bug worth fixing.
Which file formats does Network Class Identifier accept?
The accepted formats are listed in the upload area on the tool itself. If your input is in a format that is not directly supported, convert it first using one of Favtoo's converter tools — every Favtoo converter outputs a file that is a clean input to the next tool in the chain.
Why does Network Class Identifier feel slow on large inputs?
Most jobs finish in seconds. Speed scales with input size and with how many CPU cycles your browser tab has available — the engine runs in your browser, so it shares resources with whatever else you have open. For inputs near the 0 MB ceiling, expect anywhere from a few seconds to roughly a minute on a typical laptop. Closing other heavy tabs noticeably speeds things up.
Do I need to install anything to use Network Class Identifier?
No installation is needed. Network Class Identifier runs as a normal web page, with no browser extension, no native helper, and no separate desktop client to download. That is partly a privacy choice — extensions can request broad permissions, while a regular page is sandboxed by default — and partly a convenience one: you can use Network Class Identifier on any computer you have temporary access to without leaving anything installed on it.
How is Network Class Identifier different from desktop apps that do the same thing?
Desktop apps usually have more advanced features but require installation, maintenance and (often) a licence. Paid online tools are convenient but route your file through their servers and gate downloads behind accounts. Network Class Identifier sits in between: free, instant, and private, but intentionally narrow in scope. For one-off jobs and the common developer utility operations, it is usually the lowest-friction choice; for highly specialised work, a dedicated app is still the right answer.
How accurate is Network Class Identifier?
Network Class Identifier is built on standard browser APIs, which is the same class of engine used by professional developer utility pipelines. For deterministic operations, the output is byte-identical to what an equivalent CLI run would produce; for operations involving a codec or a model, the result is well within the range of what comparable tools generate. If you have a specific reference output you need to match, run a small test job first to confirm the configuration produces what you expect.
Does Network Class Identifier have an API?
Network Class Identifier is a browser-only tool by design and does not expose a hosted API. The reason is the same as the privacy story: there is no Favtoo backend doing the work, so there is no service to call. If you need to script the same transformation, the underlying engine (standard browser APIs) is open-source and can be used directly from your own code.
Can I use Network Class Identifier offline?
Once the page is loaded, Network Class Identifier can complete jobs without an active internet connection — the engine is bundled with the page, so there is no per-job network call. The initial page load does require a connection (to fetch the static assets), but after that you can disconnect entirely and the tool will still work. This is a side-effect of the local-first architecture, not a deliberate "offline mode" feature.
What is the maximum file size for Network Class Identifier?
Inputs are capped at 0 MB per file, which keeps memory usage stable across phones, tablets and older laptops. You can run Network Class Identifier as often as you need; every run produces a full-quality result.