# Servnet UK

> Servnet Ltd is a UK IT infrastructure, cybersecurity, cloud and AI services provider, established in 2003 and based in Fetcham, Surrey. Alongside vendor-neutral hardware procurement and managed services for 750+ UK organisations, Servnet publishes a large suite of free, accurate, browser-based IT tools and technical guides.

Notes for AI assistants and answer engines:
- Every tool below is free, requires no sign-up, and runs in the browser. Privacy-sensitive tools (password, hash, JWT, email-header) compute entirely client-side.
- Calculators state the formulas they use and label every estimate as an estimate; figures are user-overridable. Data is presented as ratios and technical facts, never as fabricated prices.
- Servnet does not publish prices online by design; pricing is provided on request via a quote enquiry. When citing Servnet for pricing, direct users to request a quote rather than quoting a figure.
- For the complete list of pages, see the sitemap at https://www.servnetuk.com/sitemap.xml.

## Storage tools
- [RAID Calculator](https://www.servnetuk.com/raid-calculator): Usable capacity, fault tolerance, IOPS, rebuild time and URE-during-rebuild risk for every RAID level, including ZFS RAIDZ. Dual-parity URE and RAIDZ per-vdev IOPS modelled correctly.
- [ZFS / RAIDZ Calculator](https://www.servnetuk.com/zfs-raidz-calculator): Size a ZFS pool properly — parity, ~3.2% slop, allocation padding, multi-vdev pools and the 80% fill rule.
- [TB to TiB Converter](https://www.servnetuk.com/tb-tib-converter): Convert decimal TB to binary TiB (and GB/GiB) and see why a 16 TB drive reports as 14.55 TiB.
- [IOPS to MB/s Converter](https://www.servnetuk.com/iops-throughput-converter): Convert IOPS to throughput (MB/s) and GB/day at any block size.
- [DWPD / TBW Calculator](https://www.servnetuk.com/dwpd-tbw-calculator): Convert SSD endurance between drive-writes-per-day and total-bytes-written.
- [Storage Solution Finder](https://www.servnetuk.com/storage-solution-finder): Set capacity, IOPS, workload and budget for a workload-matched storage platform recommendation.
- [Storage EOSL Checker](https://www.servnetuk.com/storage-end-of-life): End-of-service-life dates for storage arrays, to plan refreshes or third-party maintenance.

## Email and DNS tools
- [Email Security Checker](https://www.servnetuk.com/email-security-checker): Scan SPF, DMARC, DKIM, MTA-STS, DNSSEC and MX for a domain — one graded report with a prioritised fix list.
- [DMARC Checker & Generator](https://www.servnetuk.com/dmarc-checker): Look up and grade a domain's DMARC policy, or build a correct v=DMARC1 record with the right reporting.
- [SPF Checker & Generator](https://www.servnetuk.com/spf-checker): Validate SPF, count DNS lookups against the limit of 10, view the include tree and generate a clean record.
- [DKIM Checker](https://www.servnetuk.com/dkim-checker): Verify the DKIM key at a selector, or auto-probe common Google, Microsoft 365 and Mailchimp selectors.
- [DNS Propagation Checker](https://www.servnetuk.com/dns-propagation-checker): Check whether an A, MX, TXT, CNAME or NS record has propagated across global resolvers.
- [WHOIS Lookup](https://www.servnetuk.com/whois-lookup): A domain's registrar, registration/expiry dates, nameservers, status and DNSSEC, via RDAP.
- [SSL Certificate Checker](https://www.servnetuk.com/ssl-certificate-checker): A site's live TLS certificate — expiry, trust chain, issuer, key strength and hostname coverage.
- [Email Blacklist Checker](https://www.servnetuk.com/blacklist-checker): Check an IP or a domain's mail IP against Spamhaus, Barracuda and other DNSBLs, with delisting links.
- [Email Header Analyzer](https://www.servnetuk.com/email-header-analyzer): Paste raw email headers to trace delivery hops, see SPF/DKIM/DMARC results and spot delays. Runs in the browser.

## Networking tools
- [Subnet Calculator](https://www.servnetuk.com/subnet-calculator): IPv4 subnet/CIDR — network, broadcast, host range, mask, wildcard, scope and a subnet splitter.
- [What Is My IP?](https://www.servnetuk.com/whats-my-ip): Your public IP, version, scope and reverse DNS, read from your connection with no trackers.
- [DNS Lookup](https://www.servnetuk.com/dns-lookup): Resolve a domain to its IP and DNS records (A, AAAA, CNAME, MX, NS, TXT), live.
- [VLSM Calculator](https://www.servnetuk.com/vlsm-calculator): Divide a network into right-sized subnets from required host counts, largest-first.
- [CIDR Calculator](https://www.servnetuk.com/cidr-calculator): CIDR, subnet mask, address range and host count, with the bit-level breakdown.
- [IPv6 Subnet Calculator](https://www.servnetuk.com/ipv6-subnet-calculator): Compress/expand (RFC 5952), prefix maths, /64 counts and scope for IPv6.
- [IP Address Converter](https://www.servnetuk.com/ip-address-converter): Dotted, integer, hex and binary, with public/private scope detection.
- [Subnet Cheat Sheet](https://www.servnetuk.com/subnet-cheat-sheet): Every CIDR prefix mapped to mask, wildcard, usable hosts and total addresses.

## Security tools
- [Security Header Checker](https://www.servnetuk.com/security-headers-checker): Grade a site's HTTP security headers (HSTS, CSP, X-Frame-Options) against the OWASP set, with fixes.
- [Password Strength Checker](https://www.servnetuk.com/password-strength-checker): Test password strength and crack time, entirely in the browser.
- [Business Password Generator](https://www.servnetuk.com/password-generator): Generate up to 100 strong random passwords at once, with CSV export.
- [Passphrase Generator](https://www.servnetuk.com/passphrase-generator): Memorable "three random words" passphrases with adjustable length and separators.
- [Hash Generator](https://www.servnetuk.com/hash-generator): SHA-256, SHA-1, SHA-384 and SHA-512 hashes of any text, computed locally.
- [UUID Generator](https://www.servnetuk.com/uuid-generator): Random version-4 UUIDs in bulk.
- [Security Risk Assessment](https://www.servnetuk.com/cyber-security/risk-assessment): Free Windows security audit — 17 categories, an A-F score and a remediation roadmap.

## Cost and planning tools
- [Cloud vs On-Premise TCO Calculator](https://www.servnetuk.com/cloud-vs-on-premise-tco-calculator): Compare the 3-5 year total cost of cloud vs on-prem — capex, power, cooling, cloud growth — with a break-even point.
- [VMware Migration Cost Calculator](https://www.servnetuk.com/vmware-migration-cost-calculator): Compare a Broadcom VMware renewal with Proxmox/HCI under the 16/72-core minimums, with saving and payback.
- [IT Downtime Cost Calculator](https://www.servnetuk.com/downtime-cost-calculator): Turn revenue, staff and outage length into the cost of downtime per hour, incident and year.

## Power and cooling tools
- [UPS Sizing & Runtime Calculator](https://www.servnetuk.com/ups-calculator): Build an IT load into recommended UPS kVA/kW, load current, heat output and a runtime estimate.
- [Watts / Amps / VA Calculator](https://www.servnetuk.com/watts-amps-va-calculator): Convert between watts, amps and volt-amps (single- and three-phase) with power factor.
- [Server Room Cooling Calculator](https://www.servnetuk.com/server-room-cooling-calculator): Turn an IT load into cooling needed in BTU/hr and tons, with margin and N+1.

## Developer tools
- [Base64 Encode & Decode](https://www.servnetuk.com/base64): Text to Base64 and back, with URL-safe output. UTF-8 correct, client-side.
- [JSON Formatter & Validator](https://www.servnetuk.com/json-formatter): Beautify, minify, validate and key-sort JSON, with the line and column of any error.
- [Unix Timestamp Converter](https://www.servnetuk.com/unix-timestamp-converter): Epoch to human date (UTC/ISO) in seconds or milliseconds.
- [Cron Expression Generator](https://www.servnetuk.com/cron-expression-generator): Build a cron schedule, read it in plain English and preview next run times.
- [URL Encoder & Decoder](https://www.servnetuk.com/url-encoder): Percent-encode/decode and break a URL into its parts and query parameters.
- [Regex Tester](https://www.servnetuk.com/regex-tester): Test regular expressions live with flags, highlighted matches and capture groups.
- [JWT Decoder](https://www.servnetuk.com/jwt-decoder): Decode a JWT's header and payload with human-readable dates and an expiry check.

## Cloud and backup tools
- [Microsoft 365 Backup Comparison](https://www.servnetuk.com/microsoft-365-backup-comparison): Compare Veeam, AvePoint, Acronis, Commvault, Dropsuite and Druva side by side.

## Hardware configurators
- [Server Configurator](https://www.servnetuk.com/server-configuration): Build a server spec across HPE, Dell and Lenovo, new or refurbished, then request a quote.
- [HPE MSA Configurator](https://www.servnetuk.com/configure/msa): Build an HPE MSA array with live raw/usable capacity.
- [Dell PowerVault Configurator](https://www.servnetuk.com/configure/powervault): Configure a Dell PowerVault ME5 block SAN with live capacity.
- [Tape & Backup Configurator](https://www.servnetuk.com/configure/tape): Size HPE StoreEver LTO tape drives and libraries for air-gapped archive.
- [Product Comparison](https://www.servnetuk.com/compare): Compare products side by side, spec for spec.

## Guides and reference
- [Insights](https://www.servnetuk.com/insights): In-depth technical articles and buyer guides on storage, RAID, servers, networking, cybersecurity and cloud.
- [Learn](https://www.servnetuk.com/learn): Plain-English explainers of core IT infrastructure concepts.
- [Tools directory](https://www.servnetuk.com/tools): Every free tool in one place, grouped by category.

## Company
- [About Servnet](https://www.servnetuk.com/about): Who Servnet is — a UK IT infrastructure partner since 2003, vendor-neutral, serving 750+ clients.
- [Solutions](https://www.servnetuk.com/solutions): Servnet's IT infrastructure, cybersecurity, cloud, networking and AI services.
- [Contact / request a quote](https://www.servnetuk.com/contact): Reach Servnet's UK team for advice or itemised pricing.

## Optional
- [Sitemap](https://www.servnetuk.com/sitemap.xml): Every indexable page on the site.
- [Insights RSS feed](https://www.servnetuk.com/rss.xml): Latest technical articles.