Tools to calculate. Articles to explain.
Use six tools for subnet and CIDR calculations, MAC vendor lookup, checking your IP address, and converting between HTML and Markdown.
They run right in your browser, with no installation or sign-up required.
Our articles explain how networks work and how to interpret the results you get from the tools.
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// HOW TO USEChoose Series to read in order, Topics to find what you need for a task, or Articles to browse by title. Each article links to related web tools.
A longer reading path with a set order. Start with the preface, then read the articles in each part in sequence.
Browse series → // TOPICS TopicsContent grouped by what you want to do. Each topic has sections that take you straight to the articles and tools you need.
Browse topics → // KNOWLEDGE All articlesBrowse every article in book order, one row at a time. Each entry shows its series, topic, publication and modification dates, and a one-line summary.
Browse all articles → // TOOLS Free toolsAPPCalculators and converters that run in your browser. No installation or sign-up, and your input never leaves the browser.
Browse tools →A series is a continuous reading path. It starts with a preface and gradually broadens your understanding of the technology, one step at a time.
A series to read like a bookUnderstanding Network InfrastructureOpening · 6 parts · ClosingThis preface traces the endpoint–server round trip and introduces addressing, switching, routing, network design, security, and recovery.Start from the preface →Articles are grouped by topic so you can choose just the areas that interest you.
How packets find their destination
// TOPIC · four branches · 15 articlesEnterprise network designLayers and redundancy for growth and resilience
// TOPIC · four branches · 7 articlesRoutingHow paths between networks are chosen
// TOPIC · four branches · 5 articlesSwitchingHow frames travel across a local network
Recently published or updated articles. Each article shows its publication date and latest modification date.
Enter an address block in any supported format and see everything in one place. The…
7 articles · 2 tools$ html2md.html → .md converterConvert copied web content or HTML to Markdown (.md). Paste source code, paste content…
1 tool$ mac-ouiMAC vendor lookupUse the prefix of a MAC address (such as an OUI) to look up its assignee. Check…
3 articles · 1 tool$ md2html.md → .html converterEnter Markdown (.md) to preview the result as you type, then save it as a single .html…
1 tool$ myipCheck my IP addressSee the public IP address you are using to access the internet, along with connection and…
2 articles · 2 tools$ subnetIP subnet calculatorSelect either a prefix or a subnet mask. The other updates automatically, and the…
18 articles · 3 toolsYour input is not sent to a server
Calculations and searches run entirely in your browser. Even if you paste in company IP addresses or configuration files, they are not sent to or stored on a server. We analyze visits and usage only within the scope described in the Privacy Policy, and we do not include your inputs in those statistics.
We run and verify what we publish
We include only commands and figures we have actually run and reproduced. Tool examples are published after comparison with standard test values. We do not publish what we have not verified.
We record corrections and their history
This site is run directly by a company that has developed enterprise software and designed and deployed wired and wireless networks since 2016. When we correct an error, we record the change and its date.
Who we are
// ABOUTSince 2016, IM Business Platform Co., Ltd. has developed software tailored to enterprise requirements and designed, deployed, and maintained enterprise wired, wireless, and security networks. Building on our representative director's background in product planning, we also advise IT and cybersecurity companies on product planning and quality assurance.
Drawing on this experience, we created and run this site to bring together the tools and information that IT work calls for regularly but that can be hard to find.
The site does more than offer a tool or a piece of information. It connects the underlying principles, ways to interpret the results, and the tools you need. You get not just an answer, but help understanding what it means.