32 free tools, with more on the way
Free online tools
that just work.
Security checks, network tests, generators and calculators for IT pros, businesses and anyone else who needs a job done. No sign-up, no paywall.
- Tools
- 32+
- Cost
- £0
- Sign-ups
- None
- Categories
- 6
Spotlight
Flagship tools
The tools we're building first, all designed for speed and privacy.
Secure Shared Clipboard Transfer
Share text, passwords, screenshots and files between two computers with a private link. Encrypted, and wiped after 48 hours.
Smart QR Code Generator
QR codes for links, Wi-Fi, contacts and more, in your own colours, as PNG or SVG.
Cyber Essentials Checker
Work through the 2026 Danzell question set, see exactly which answers would fail (including the new automatic fails), and keep an evidence log book you can save, share and print.
True Speed & Lag Test
Your real download and upload speed, plus how much lag builds up when the line is busy and what that does to video calls, gaming and phone calls.
The toolbox
All tools
Search or filter by category. New tools are added regularly.
1 of 32 tools
Secure Shared Clipboard Transfer
Share text, passwords, screenshots and files between two computers with a private link. Encrypted, and wiped after 48 hours.
Cyber Essentials Checker
Work through the 2026 Danzell question set, see exactly which answers would fail (including the new automatic fails), and keep an evidence log book you can save, share and print.
Cyber Essentials Plus Readiness
Get ready for the Cyber Essentials Plus audit: every self-assessment question plus the seven technical tests the assessor runs, with what to check before they arrive.
Enhanced Security Readiness Audit
A 27-area audit well beyond Cyber Essentials: AI tools and agents, Microsoft 365 and Google integrations, deepfake and phishing-kit attacks, cloud servers with weekly testing, pen testing, backups and incident response.
Browser Fingerprint Test
See the 100+ details your browser gives away, and test whether websites can recognise you across private windows and VPNs without cookies.
Password Generator
Strong random passwords and memorable passphrases, generated in your browser.
Password Strength Tester
See how long a password would take to crack. It never leaves your device.
Email Security Checker
Check a domain's SPF, DKIM and DMARC setup, plus MTA-STS, TLS reporting and BIMI, against Google, Microsoft and NCSC requirements, with the records to fix it.
Email Header Analyser
Paste an email's headers to trace the servers it passed through, check SPF, DKIM and DMARC, decode spam filter verdicts and spot spoofed or hijacked senders.
SSL Certificate Checker
Inspect a site's certificate, its expiry date, the full chain and the TLS versions it supports.
Hash Generator
Create SHA-1, SHA-256, SHA-384 and SHA-512 hashes of text or files.
True Speed & Lag Test
Your real download and upload speed, plus how much lag builds up when the line is busy and what that does to video calls, gaming and phone calls.
Internet Stability Checker
Watch your connection for 1 to 10 minutes to catch lag spikes, jitter and dropouts, then see whether it's good enough for gaming, calls and streaming.
What's My IP
Your public IP address, who your internet provider is, your reverse DNS and what your browser reveals about you.
ISP Leak & Blocking Detector
Check whether your internet provider or VPN is leaking your real IP through WebRTC, or blocking websites on your connection.
DNS Leak Checker
See which DNS servers really answer your lookups, so you can tell if your VPN or private DNS is leaking.
DNS Checker & Propagation
Look up any DNS record, compare answers across six public resolvers and the authoritative servers, trace a lookup from the root and check DNSSEC.
Domain WHOIS Lookup
Who a domain is registered with, when it was registered and when it expires, its status locks, nameservers and where it's hosted. Works for .com, .co.uk and most other endings.
Subnet Calculator
Work out network ranges, masks, broadcast addresses and usable hosts.
HTTP Header Checker
See any website's redirect chain and response headers, with a security header grade, cookie and caching checks, certificate expiry and HTTP/2 support.
Ethernet Cable & PoE Calculator
Will a cable run carry the speed and PoE power you need? Check Cat5e to Cat8 against 1 to 40 Gbps, work out voltage drop and power loss, and find the longest run that works.
Smart QR Code Generator
QR codes for links, Wi-Fi, contacts and more, in your own colours, as PNG or SVG.
Bitcoin Paper Wallet Generator
Create a Bitcoin address and private key offline in your browser and print them as a paper wallet with QR codes.
UUID Generator
Random v4 and time-ordered v7 UUIDs (GUIDs), plus v1, v6, v3 and v5, one at a time or up to 10,000 at once. Decode any UUID to see its version and time.
JSON Formatter & Validator
Format, minify and validate JSON with exact error locations and plain-English fixes, one-click repair, sorted keys, a tree view and big numbers kept exact.
Base64 Encoder / Decoder
Encode text and files to Base64, or decode Base64 back to text, images or files. URL-safe, MIME and data URIs, with file type detection and JWT decoding.
Unix Timestamp Converter
Convert Unix timestamps in seconds, milliseconds or nanoseconds to dates in any time zone and back, plus Excel, Windows and .NET times and whole log files.
Colour Converter & Contrast
Convert between HEX, RGB and HSL, and check WCAG contrast between two colours.
PC Skills & Competency Test
Test everyday computer, Microsoft 365, Word, Excel, Outlook and online safety skills. Marked instantly with explanations and a printable, verifiable result.
UK VAT Calculator
Add or remove VAT at 20%, 5% or a custom rate.
Download Time Calculator
How long a file, game, film or backup takes to download or upload at your speed, compared across UK connections, and the speed you need to hit a deadline.
Percentage Calculator
Percentages of numbers, percentage change, increases and decreases.
No tools match that search yet
Try a different word or category. We're adding new tools all the time.
Show all toolsWhy osir
Built by IT pros, free for everyone
Free, for good
Every tool is free to use. There are no trials, credits or premium tiers.
No sign-up
Open a tool and use it. No accounts, emails or passwords.
Private by design
Where possible, tools run in your browser, so your data never leaves your device.
Fast and lightweight
Hand-written code with no frameworks, ads or third-party trackers. It works on any device.
Brought to you by
Made possible by our partners
osir's free tools are built and supported by three technology companies.