440 tools · nothing uploaded
Test your device, connection and privacy. Free, in your browser.
No downloads and no sign-up. Every result tells you what it could not measure as well as what it could.
Build status
Tools live440
Categories26
Largest categories
- Device73 live
- Connection46 live
- Printer42 live
- Interpreter24 live
- DevTools20 live
- Runs entirely in your browser
- No sign-up, no uploads
- Free
Browse by category
440 tools across 26 categories.
- Device73 toolsAccelerometer / Shake Test · Aspect Ratio Calculator · Audio Dropout Monitor
- Connection46 toolsProxy / VPN Signal Check · Bandwidth Converter · Bufferbloat / Latency Under Load Test
- Printer42 toolsBarcode Print Readability Test · Black & White / Mono Test Page · Print Margin & Bleed Calculator
- Interpreter24 toolsWindows Battery Report Interpreter · Windows Stop Code / BSOD Lookup · VoIP & Gaming Quality Grader
- DevTools20 toolsArduino / ESP Board Detector · ASCII Table Reference · .htaccess Rule Generator
- SysAdmin19 toolsBackup Window Calculator · Bandwidth Cost Calculator · Bandwidth per User Planner
- NetMath19 toolsBandwidth-Delay Product / TCP Window · CIDR to IP Range · HTTP Status Code Reference
- DevOps17 toolsAPI Rate Limit Calculator · X.509 Certificate Decoder · CSV to JSON Converter
- SEO17 toolsImage Alt Text Auditor · Duplicate Content Comparer · Heading Structure Auditor
- Repair16 toolsBattery Health Estimator · POST Beep Code Reference · Full Diagnostic Report Export
- Security15 toolsBase64 Encoder / Decoder · Bulk Password Generator · File Checksum Verifier
- Privacy14 toolsAd Blocker Detector · Audio Fingerprint · Bot / Automation Signals
- QR14 toolsBulk QR from CSV · Custom / Branded QR (logo, colour) · Email QR Code
- Data13 toolsCSV Deduplicator · CSV Splitter · CSV to HTML Table
- Text13 toolsAdd Line Numbers · Case Converter · Character Counter
- WebAudit12 toolsDNS Blacklist (RBL) Checker · Broken Link Checker · Canonical & hreflang Checker
- Calc10 toolsBreak-Even Calculator · Data Size Converter · Discount Calculator
- Image9 toolsBarcode Reader · Blur / Pixelate (redaction) · EXIF Data Viewer
- Label9 toolsAddress Label Sheet · Barcode Label Sheet PDF · Bulk Barcode from CSV
- Time9 toolsCountdown Timer · Cron Expression Parser · Date Difference Calculator
- Audio8 toolsBPM Tapper · dB / Sound Level Meter · Guitar Tuner
- WebSec6 toolsCookie Security Check · CSP Generator · Password Policy Generator
- Colour5 toolsColour Blindness Simulator · HEX / RGB / HSL / CMYK Converter · Palette Generator
- Frontend4 toolsBox Shadow Generator · CSS clamp() Calculator · CSS Grid Generator
- Email4 toolsEmail Bounce Code Decoder · DMARC Record Generator · SPF Record Generator
- Marketing2 toolsAd RPM / Revenue Calculator · UTM Link Builder
Available now
- Accelerometer / Shake TestCheck the accelerometer responds, and see the peak force in g as you move.
- Aspect Ratio CalculatorWork out the aspect ratio of any resolution — and what it is commonly called.
- Audio Dropout MonitorCatch the moments your audio thread starves — the cause of most crackles and gaps.
- Echo / Loopback TestFind out whether the person you are calling can hear themselves through you.
- A/V Sync (Lip-Sync) TestMeasure how far your sound is ahead of or behind the picture, in milliseconds.
- Backlight Bleed TestCheck for backlight bleed on a full-black field — and tell it apart from IPS glow.
- Proxy / VPN Signal CheckCheck whether your traffic is being rerouted — and see what sites see.
- Bandwidth ConverterConvert between Mbps, MB/s and everything in between.
- Bufferbloat / Latency Under Load TestFind out whether your connection falls apart when somebody else is downloading.
- CAA Record CheckerSee which certificate authorities are allowed to issue for a domain.
- Which CDN Datacenter (colo)See which Cloudflare data centre is serving you.
- CNAME Chain TracerTrace a domain’s CNAME alias chain to where it finally points.
- Barcode Print Readability TestPrint a barcode grid to check scannability.
- Black & White / Mono Test PagePrint a monochrome density and text test.
- Print Margin & Bleed CalculatorWork out artboard, bleed and safe area for a print job.
- Borderless Print TestPrint a full-bleed pattern to test borderless output.
- Brother Printer Test PagePrint a full test sheet for your Brother printer.
- Canon Printer Test PagePrint a full test sheet for your Canon printer.
- Windows Battery Report InterpreterTurn a Windows battery report into the one number it buries: capacity remaining.
- Windows Stop Code / BSOD LookupLook up a Windows blue-screen stop code and get the likely cause and next step.
- VoIP & Gaming Quality GraderGrade a connection for calls, gaming and streaming against real thresholds.
- CPU-Z / GPU-Z Report InterpreterRead a CPU-Z report and spot the two numbers everyone misreads.
- Drive Age & Power-On Hours AnalyserTurn power-on hours into a realistic picture of drive age.
- dxdiag Report InterpreterFind the four lines in a DxDiag report that explain why a game will not run.
- Arduino / ESP Board DetectorIdentify a board from its USB IDs — and be told plainly when only the bridge chip is known.
- ASCII Table ReferenceLook up any character’s ASCII code in every base.
- .htaccess Rule GeneratorDescribe the rules you want and get a valid .htaccess block.
- HTML Entity Encoder / DecoderEncode or decode HTML entities, whichever the text needs.
- HTML to MarkdownTurn a page of HTML into readable Markdown.
- JSON Compare / DiffDiff two JSON documents structurally instead of by text.
- Backup Window CalculatorWork out whether a backup job finishes before the window closes.
- Bandwidth Cost CalculatorEstimate what outbound data transfer costs you each month.
- Bandwidth per User PlannerSize an internet connection on the people using it at once.
- chmod / Permission CalculatorConvert Unix file permissions between octal, symbolic and plain English.
- Cloud vs On-Prem Storage CostFind the month a NAS stops costing more than a cloud subscription.
- Crontab GeneratorBuild a cron schedule and read it back in English — including the day-field trap.
- Bandwidth-Delay Product / TCP WindowFind how much data must be in flight to keep a long link busy.
- CIDR to IP RangeExpand any CIDR block into its network, broadcast and usable host range.
- HTTP Status Code ReferenceLook up any HTTP status code — what it means and when you actually see it.
- IP Range to CIDRTurn a start and end address into the fewest CIDR blocks that cover it.
- IP to Decimal / Hex / BinaryConvert an IPv4 address to its integer, hex and binary forms, and back.
- IPv4 to IPv6 MapperConvert an IPv4 address to its IPv6 representations.
- API Rate Limit CalculatorSize a request rate that fits inside a quota, retries included.
- X.509 Certificate DecoderDecode a PEM certificate and read every field it carries.
- CSV to JSON ConverterConvert CSV to JSON without destroying your identifiers.
- cURL Command BuilderAssemble a curl command with the shell quoting done properly.
- cURL Command ParserRead a curl command back in plain terms, and convert it to fetch or Python.
- Diff / Text CompareCompare two blocks of text and see exactly what changed.
- Image Alt Text AuditorFind images with no alt text — and the ones whose alt text says nothing.
- Duplicate Content ComparerCompare two pages and see exactly which passages they share.
- Heading Structure AuditorSee a page's heading outline and find the skipped levels nobody can see.
- hreflang Tag GeneratorBuild a reciprocal hreflang set for a multilingual page.
- Meta Robots & Indexability CheckerDecode every robots directive on a page and find the one keeping it out of search.
- Internal Link AuditorAudit the links on a page, including the anchors that describe nothing.
- Battery Health EstimatorWork out your battery’s real health from its capacity figures.
- POST Beep Code ReferenceLook up what a POST beep pattern means, and what to try first.
- Full Diagnostic Report ExportEvery silent check in one run, exported as a dated PDF for tickets, claims and resale.
- Game Crash Log InterpreterFind the likely culprit in a game crash log.
- IMEI Checksum ValidatorCheck whether an IMEI is internally valid before you trust a listing.
- Mac Startup Symbol ReferenceWhat each Mac startup symbol means, and which stage of boot it points at.
- Base64 Encoder / DecoderEncode text to Base64 or decode it back — UTF-8 safe, in your browser.
- Bulk Password GeneratorGenerate a list of random passwords at once, for provisioning rather than for one account.
- File Checksum VerifierVerify a download's checksum without uploading the file anywhere.
- Hash GeneratorGenerate SHA-1, SHA-256, SHA-384 or SHA-512 hashes of text, in your browser.
- HMAC GeneratorCompute an HMAC, and see why it is not a hash of the key and the message.
- Memorable Password GeneratorPronounceable passwords, with the entropy that pronounceability actually costs.
- Ad Blocker DetectorSee the exact technique sites use to detect your ad blocker — without being nagged by it.
- Audio FingerprintSee the audio-stack fingerprint your browser produces — computed silently, never played.
- Bot / Automation SignalsSee the automation signals your browser reports — and why none of them proves anything.
- Fingerprint Uniqueness ScoreSee the signals that identify your browser without a single cookie.
- Storage InspectorSee exactly what this site has stored on your device — and why it cannot see any other.
- Canvas Fingerprint ViewerSee the canvas fingerprint your browser hands to any site that asks.
- Bulk QR from CSVGenerate hundreds of QR codes from a pasted list — none of it uploaded.
- Custom / Branded QR (logo, colour)Branded QR codes with your colours and logo — and a warning when they stop scanning.
- Email QR CodeA QR code that opens a new email with the address, subject and body filled in.
- Calendar Event QRA calendar event as a QR code, with times written in UTC so they survive travel.
- Location / Geo QRA QR code for a map location — and why a plain link is often more reliable.
- Phone Number QRA QR code that opens the dialler with a number ready — no call is placed.
- CSV DeduplicatorRemove exact duplicate rows and flag the conflicting ones.
- CSV SplitterSplit a long CSV into parts that each keep the header.
- CSV to HTML TableConvert a CSV into accessible, escaped HTML table markup.
- CSV to Markdown TableTurn a CSV into a Markdown table, with pipes escaped properly.
- CSV to XLSXTurn a CSV into a workbook without letting the spreadsheet mangle your data.
- CSV ViewerView a CSV as a table — and find the rows that do not line up.
- Add Line NumbersAdd sequential line numbers to text.
- Case ConverterConvert text between UPPER, lower, Title, camelCase, snake_case and more.
- Character CounterCount characters, words and lines as you type.
- Find and ReplaceFind and replace text, counting every match.
- Reading Time CalculatorEstimate how long text takes to read.
- Remove Duplicate LinesRemove duplicate lines, keeping the first of each in order.
- DNS Blacklist (RBL) CheckerCheck an IP against the major blocklists — and see which refused to answer.
- Broken Link CheckerCheck the links on a page and find the ones that no longer resolve.
- Canonical & hreflang CheckerCheck whether a page can actually be indexed — and what it says about itself.
- Certificate Transparency SearchEvery hostname anyone has ever certified for a domain — already public.
- CMS & Version DetectorIdentify what built and serves a page — with the evidence for each finding.
- Multi-Resolver DNS PropagationCompare three public resolvers — conclusive when they disagree, honest when they agree.
- Break-Even CalculatorFind how many units you must sell to cover your costs.
- Data Size ConverterConvert between bytes, KB, MB, GB and TB — decimal and binary, side by side.
- Discount CalculatorWork out a sale price and how much you save.
- Percentage CalculatorThe three percentage questions people actually ask — each with its own formula.
- Profit Margin & Markup CalculatorCalculate profit margin from cost and sale price.
- Random Number GeneratorGenerate random numbers in a range, without modulo bias.
- Barcode ReaderDecode a barcode from a photo, using the browser's own detector.
- Blur / Pixelate (redaction)Redact part of an image — and see why blurring is not redaction.
- EXIF Data ViewerSee every EXIF field in a photo — shooting settings and identifying data, kept apart.
- Favicon / ICO GeneratorA real multi-size favicon.ico plus the PNGs modern browsers use — no upload.
- HEIC to JPG ConverteriPhone photos into JPGs that open everywhere — converted in your browser, in batches.
- Image CompressorShrink a photo in your browser. The file is never uploaded.
- Address Label SheetPrint address labels at real millimetre sizes, measured rather than guessed from a preset.
- Barcode Label Sheet PDFA printable sheet of barcodes, optionally numbered in sequence.
- Bulk Barcode from CSVTurn a pasted list or CSV column into a printable sheet of barcodes.
- Barcode Check Digit CalculatorCalculate or verify the check digit on a barcode number.
- Code 128 GeneratorGenerate a Code 128 barcode that will actually scan at the size you print it.
- Code 39 GeneratorGenerate a Code 39 barcode — the symbology every scanner reads without configuration.
- Countdown TimerA countdown that stays accurate when the tab is in the background.
- Cron Expression ParserRead a cron expression in plain English and see when it next runs.
- Date Difference CalculatorDays, weeks, months and weekdays between two dates — counted the way people mean.
- Epoch / Unix Timestamp ConverterConvert a Unix timestamp to a date and back — in UTC, unambiguously.
- Interval / HIIT TimerRun work and rest intervals with a tone at each change.
- Meeting Timezone PlannerFind the hours a distributed team can actually meet.
- BPM TapperTap along to find a track's tempo, using the median so early taps stop counting.
- dB / Sound Level MeterA level meter that reports dBFS honestly, because a browser cannot measure sound pressure level.
- Guitar TunerTune a guitar by ear-free measurement — cents, not colours, and no app.
- MetronomeA metronome scheduled on the audio clock, so it does not drift the way browser timers do.
- Instrument TunerA chromatic tuner for any instrument — note, frequency and cents.
- Pitch DetectorDetect the pitch of any sustained note, in hertz and in cents from the nearest note.
- Cookie Security CheckAudit Set-Cookie headers for Secure, HttpOnly and SameSite.
- CSP GeneratorBuild a Content-Security-Policy that is worth deploying — starting in report-only.
- Password Policy GeneratorWrite a password policy that reflects current guidance, not 2005.
- Permissions-Policy BuilderBuild a Permissions-Policy header that constrains the third-party code you did not write.
- security.txt CheckerCheck a security.txt file against RFC 9116, including the expiry that makes it valid.
- SRI Hash GeneratorGenerate a Subresource Integrity hash for a script or stylesheet.
- Colour Blindness SimulatorSee a design through the four colour vision deficiencies — simulated in linear light.
- HEX / RGB / HSL / CMYK ConverterConvert a colour between HEX, RGB and HSL.
- Palette GeneratorHarmonies from one colour, each swatch carrying the contrast it can actually deliver.
- Colour PickerPick a colour, get every format, its tints and shades, and its real contrast.
- Contrast Checker (WCAG)Check colour contrast against WCAG AA and AAA — the exact ratio, not an estimate.
- Box Shadow GeneratorBuild a box-shadow that reads as light rather than a smudge.
- CSS clamp() CalculatorGenerate a clamp() value that scales type between two viewports.
- CSS Grid GeneratorBuild a grid that reflows on its own, with no media queries.
- Flexbox PlaygroundGet flexbox CSS, and see which axis each property is talking about.
- Email Bounce Code DecoderRead what a bounce message actually says, and whether it will retry.
- DMARC Record GeneratorBuild a DMARC record — starting where you should, not where you want to end.
- SPF Record GeneratorBuild an SPF record and count the lookups before it breaks.
- SPF Lookup CounterCount the DNS lookups your SPF record really costs — the limit is ten.
Tools that say what they can't measure
Most online "test" tools overstate what a web page can do — promising to read your drive's health, your battery, or your printer's ink from a browser that has no access to any of it. Everything here runs client-side and is honest about the line between what it measures and what it estimates. Where a figure is an approximation, the result says which approximation and why it differs from the real thing.
Runs in your browser
No account, no install, no upload endpoint. For most tools you can confirm in your network panel that nothing leaves the page.
Honest about limits
Every result carries a "what this cannot tell you" note. A browser can't read your hardware, and we say so rather than guessing.
Fixes before hardware
When a test fails, free fixes come first. A failed test is never an excuse to sell you hardware you don't need.
Frequently asked questions
Are these tools really free, with no sign-up?
Yes. Every tool runs in your browser with no account, no email and nothing to install. Some pages carry advertising or affiliate links, disclosed where they appear, but nothing is gated behind a sign-up or a paywall.
Is anything I test or paste uploaded to a server?
For the great majority of tools, no — they compute entirely in your browser, and you can confirm in your network panel that nothing is sent. The few tools that must reach out (a DNS lookup, a site-reachability check) say so on the page and only send the specific thing you asked them to check, never your files.
Why can't a browser read my hardware directly?
Browsers deliberately block access to drive health, installed RAM, CPU temperature, fan speed, true battery health and printer ink levels, for privacy and security reasons. Any site claiming to read those from a web page is guessing. Our tools that touch hardware work from figures you read out of your own system report, or diagnose visually from what you print or see — and each one says plainly what it cannot measure.
Do you ever ask me to run a command or paste something into a terminal?
Never. Some tools interpret output you already produced — a ping run, an error code, a battery report — but the site does not distribute, link to, or instruct you to run any script or command, because "paste this into your terminal" is exactly how the most common malware spreads. If a page here ever asks that, it has been tampered with.