AI troubleshooting
Gemini Error Checker
Troubleshoot Gemini error 1155, failed messages and uploads. Check attachment sizes locally and copy a practical troubleshooting report.
Gemini 1155TroubleshootingFile uploadError report
Live tools only
Online checker tools ready to use
This directory lists only live checkers on CheckToolkit. Filter by category, open the tool you need, and follow related links from each tool page.
Find a Tool on CheckToolkit
Explore 43 CheckToolkit checker tools. Search by keyword or filter by category to find the right tool faster.
Image
Image Checker
Upload an image and check dimensions, aspect ratio, file size, DPI, metadata and common social media or SEO image requirements in your browser.
Image sizeSocial mediaDPIMetadata
Passport photos
Passport Photo Size Checker
Upload a passport or visa photo to pre-check dimensions, aspect ratio, file size, background cleanliness, head centering, face size and crop fit for common photo presets.
Passport photoVisa photoPhoto sizeCrop check
Passport photos
Passport Photo Print and Scan Checker
Upload a scanned passport photo sheet or single scanned print to check print scale, paper size, DPI, scan crop, page margins, white borders and physical size drift.
Passport photoPrint scaleScan DPIPhysical size
Image
Profile Picture Safe Zone Checker
Upload an avatar, logo or portrait to preview circular crops, square avatars, 32 x 32, 48 x 48 and 96 x 96 sizes, safe-zone padding and dark or light backgrounds.
AvatarSafe zoneCircle cropSmall preview
Files and uploads
File Attachment Checker
Upload PDF, DOCX, PNG, JPG, ZIP, CSV and other attachments to check file name safety, extension, size, MIME type, detected type and common form-upload risk before submission.
File uploadAttachmentsMIME typeForm submission
Files and uploads
CSV File Checker
Upload a CSV file to check delimiter, encoding, consistent columns, duplicate headers, blank rows, quote errors, long fields and spreadsheet or database import risks.
CSVDelimiterEncodingImport QA
Files and uploads
PDF Page Size Checker
Upload a PDF to check total pages, per-page dimensions, A4, Letter, Legal or A5 paper type, portrait or landscape orientation, mixed sizes and printing crop risk.
PDFPage sizePrint checkA4 Letter
Image
Thumbnail Safe Zone Checker
Upload a video thumbnail, course cover or blog cover to preview safe-zone masks, crop risk, player overlays, duration badge conflicts and mobile readability.
ThumbnailSafe zoneCrop riskReadability
Web and SEO
JSON Checker
Validate, format, minify, and check JSON files for syntax errors, trailing commas, duplicate keys, structure, and file size in your browser.
JSONFile checkDuplicate keysTrailing commas
Web and SEO
HTML Head Checker
Paste HTML head code to check SEO and pre-launch issues such as title, meta description, canonical, hreflang, viewport, robots, favicon, Open Graph, Twitter Card, language, charset and duplicate tags.
HTML headSEOHreflangLaunch QA
Web and SEO
On Page SEO Checker
Paste body HTML, article content or a CMS export to check heading structure, H1-H6 counts, image alt text, anchor text, duplicate links and target blank noopener issues.
On-page SEOHeadingsAlt textLinks
Web and SEO
Favicon & App Icon Checker
Upload a logo, favicon, app icon or PWA icon to check square shape, dimensions, transparency, file size and common favicon, Apple touch, PWA and Android icon needs.
FaviconApp iconPWAApple touch
Web and SEO
URL and UTM Checker
Paste URLs, page slugs or campaign links to check URL structure, slug format, UTM completeness, duplicate parameters, empty values, encoding, length and privacy-risk query data in your browser.
URL QAUTMSlug checkPrivacy
Web and SEO
Open Graph Tag Checker
Paste HTML, head code or manual social meta fields to check missing Open Graph tags, Twitter Cards, duplicate tags, image URL issues, canonical status and share preview fit.
Open GraphSocial previewTwitter CardSEO
Web and SEO
Robots and Sitemap Checker
Paste or upload robots.txt, sitemap.xml or sitemap index content to check crawl rules, dangerous Disallow patterns, XML validity, duplicate URLs, empty loc values and lastmod warnings.
robots.txtSitemap XMLTechnical SEOCrawl QA
Web and SEO
Schema Markup Checker
Paste JSON-LD, Microdata or full HTML to check SEO structured data types, missing common fields, duplicate schema, URL warnings, image gaps, FAQ structure and BreadcrumbList hierarchy.
SchemaJSON-LDMicrodataStructured data
Files and uploads
Config File Checker
Paste or upload YAML, TOML and ENV files to check file type, indentation, duplicate keys, empty values, invalid ENV names, duplicate TOML sections and cleanup suggestions locally.
YAMLTOMLENVConfig QA
Web and SEO
Regex Pattern Checker
Paste a JavaScript regular expression and test text to validate syntax, flags, brackets, escapes, matches, capture groups, named groups, positions and regex risk warnings locally.
RegexJavaScriptCapture groupsLog QA
Web and SEO
JWT Claims Checker
Paste a JWT token to decode header and payload claims locally, check three-part structure, exp, nbf, iat, issuer, audience, subject and alg none warnings without verifying signatures.
JWTClaimsAPI debugAuth
Web and SEO
Cron Expression Checker
Paste a 5-field cron expression to check field count, minute, hour, day, month and weekday ranges, step values, explanations, warnings and the next 5 run times locally.
CronAutomationDevOpsGitHub Actions
Web and SEO
Log Line Checker
Paste logs, errors, terminal output or API debug text into this Log Line Checker to spot common sensitive patterns such as tokens, passwords, keys, emails, IPs, database URLs, SQL errors and stack traces locally.
LogsSecretsRedactionSupport QA
Files and uploads
File Privacy and Metadata Checker
Upload PDF, DOCX, PPTX, XLSX and ZIP files to inspect document metadata, Office core properties, PDF Creator and Producer values, XMP metadata, hidden archive files and privacy leak risks locally.
MetadataPDFOfficeZIP privacy
Files and uploads
File Hash and Checksum Checker
Upload one or more files to generate SHA-256, SHA-384, SHA-512, SHA-1 and MD5 locally, then paste an official checksum to compare exact and cleaned matches.
SHA-256MD5ChecksumFile integrity
Web and SEO
Password Strength and Policy Checker
Enter a password to check local strength, weak patterns, common policy fit, account password suitability and master password suitability without uploading it.
Password strengthPolicy checkWeak patternsLocal privacy
Web and SEO
Security Headers and CSP Checker
Paste HTTP response headers, curl -I output, Cloudflare, Vercel or Nginx headers to check missing security headers, CSP risks, HSTS max-age and copyable fixes locally.
Security headersCSPHSTSHTTP
Web and SEO
DNS and Email Records Checker
Enter one or more domains to query DNS-over-HTTPS records and review DNS basics, MX, SPF, SPF lookup count, DMARC, DKIM selectors, CAA records, provider hints and repair suggestions.
DNSMX SPF DMARCDKIM CAADoH
Web and SEO
Email Header Checker
Paste raw email headers into this Email Header Checker to parse Authentication-Results, Received, From, Return-Path, Reply-To and Message-ID locally, then review SPF, DKIM, DMARC, forwarding and spoofing clues.
Email headersSPF DKIM DMARCReceived chainLocal parsing
Web and SEO
DNS Zone File Checker
Paste a DNS zone file, Cloudflare DNS export or bulk DNS records to check A, AAAA, CNAME, MX, TXT, NS, SOA, CAA, CNAME conflicts, duplicate SPF, DMARC, DKIM, TTL, wildcard and trailing-dot migration risks locally.
DNS zone fileCloudflare exportMigration QALocal check
Files and uploads
ATS-Friendly Resume Checker
Upload a PDF or DOCX resume, or paste resume text, then check local ATS readability, extracted text, scanned-text risk, layout risk, sections, contacts, JD keyword match and bullet quality without fake ATS scores.
ResumeATSPDF DOCXJob search
Files and uploads
PDF Text Layer and Redaction Checker
Upload a PDF to check selectable text, scanned-page risk, low text coverage, black-box redaction overlays, hidden text, annotations, forms, attachments and rotation locally.
PDF text layerRedactionOCR reviewLocal PDF
Image
QR Code Print Readability Checker
Upload a QR code image to check local scan readability, decoded content preview, image size, quiet zone, contrast, blur, crop risk, logo obstruction and minimum print size.
QR codePrint checkQuiet zoneLocal scan
Web and SEO
SVG Safety and Icon Use Checker
Paste or upload SVG code to check XML validity, scripts, event attributes, foreignObject, external resources, base64 embeds, viewBox, dimensions, accessibility and icon-use risks locally.
SVGIcon safetyviewBoxAccessibility
Web and SEO
PWA Manifest Checker
Paste or upload manifest.json to check Web App Manifest fields, installability settings, icon declarations, screenshots, shortcuts, colors, start_url and scope risks locally.
PWAManifest JSONInstallabilityIcons
Web and SEO
Ads.txt and App-ads.txt Checker
Paste ads.txt or app-ads.txt content to check authorized sellers file fields, ad system domains, seller IDs, DIRECT or RESELLER values, duplicates and cleanup suggestions locally.
ads.txtapp-ads.txtAuthorized sellersAdTech QA
Web and SEO
RSS and Atom Feed Checker
Paste or upload RSS or Atom XML to check feed type, XML parsing, feed title, site link, item and entry count, missing fields, duplicate links, duplicate guid values, dates, titles and enclosures locally.
RSSAtomFeed XMLPodcast basics
Files and uploads
ICS Calendar File Checker
Upload or paste an .ics calendar file to check VCALENDAR, VEVENT, UID, SUMMARY, DTSTART, DTEND, DURATION, RRULE, EXDATE, TZID, all-day format and import risks locally.
ICSCalendar importVEVENTRRULE
Web and SEO
HTML Email Template Checker
Paste an HTML email template to check preheader, image alt text, external CSS, inline style coverage, mobile width, Outlook compatibility risk and dark mode reminders locally before sending newsletters, marketing emails, codes, confirmations or notifications.
HTML emailNewsletterPreheaderOutlook risk
Web and SEO
Markdown and Front Matter Checker
Paste Markdown, MDX, blog posts, README files or docs pages to check H1-H6 headings, YAML front matter, code fences, tables, lists, image alt text, links and a publishing checklist locally.
MarkdownFront matterMDXDocs QA
Web and SEO
Encoded Text and Data URL Checker
Paste Base64, Base64URL, URL encoded text, HTML entities, Data URLs, copied mojibake or API encoded fragments to detect likely encodings, decode locally, inspect MIME type, invisible characters, double encoding and privacy-risk hints.
Base64Data URLHTML entitiesLocal decode
Web and SEO
SQL Query Safety Checker
Paste SQL into this SQL Query Safety Checker to review DELETE or UPDATE without WHERE, DROP, TRUNCATE, multi-statements, SELECT *, missing LIMIT, hardcoded secrets and before-run risks locally.
SQL safetyDELETE UPDATEDatabase QALocal check
Files and uploads
Package and Release File Checker
Paste or upload package.json, pyproject.toml, composer.json, Cargo.toml, README and CHANGELOG files to check release metadata, docs, changelog structure and checklist gaps locally.
Package releaseREADMECHANGELOGLocal check
Minecraft
Minecraft Locator Bar Color Checker
Paste a Minecraft UUID or an offline username to find the exact Locator Bar dot color, hex and RGB the Java Edition client derives from the player UUID, locally in your browser.
MinecraftLocator barUUID colorJava Edition
Tools FAQ
What can I check with CheckToolkit?
CheckToolkit helps you check practical details before you upload, publish or send something. Current tools focus on image checks such as dimensions, aspect ratio, file size, DPI, metadata and common publishing requirements.
Are CheckToolkit tools free to use?
Yes. The tools listed here are free to use and do not require an account.
Does CheckToolkit store my uploaded files?
When a check can run in your browser, CheckToolkit keeps the file on your device. Each tool page explains what it needs to read and whether any network request is required.
How do I find the right CheckToolkit checker tool?
Use the search box to look for a task, file type or requirement, or filter by category such as image, passport photos, or web and SEO.
Can CheckToolkit results replace official requirements?
No. CheckToolkit is meant to catch common issues earlier, but the final standard is still the requirement from the platform, school, client, visa center or other official source.
Why does CheckToolkit have only a few tools in some categories?
CheckToolkit adds tools when they can solve a real task clearly. The directory avoids placeholder pages, so new checker tools appear as they become useful.
Need another check?
Jump back to the tools directory and choose the checker that matches your next task.