$ ./internalhost-tools.sh

IT tools

A handful of free tools for sysadmins and developers. Everything runs client-side in your browser — nothing goes to our servers, nothing gets logged. View source to verify.

Client-side Server-side 30 req/min

Tools & diagnostics

AS204729 · Qupra DC · Amsterdam

Looking Glass

In your browser

Subnet, JWT, JSON, hashes — Web Crypto in your tab. No requests to us.

▸ Subnet calculator

Compute network, broadcast, first/last host, usable address count. Works for IPv4 and IPv6. Example: our own .

▸ Password generator

Uses window.crypto.getRandomValues() — not Math.random(). Click the result to copy.

copied.

▸ UUID generator

crypto.randomUUID() — RFC 4122 v4. Generate 1, 10 or 100 at once.

▸ JWT decoder

Decode and inspect header + payload of a JSON Web Token. Flags expired tokens. No signature validation (that requires the secret).

Header

                                

                                

                                    
Payload

                                    

                                

                                

                                     ()
                                

                            

                        

                    

                


                

                    
                        
                            ▸
                            JSON formatter
                        
                        
                    
                    

                        
Format with 2- or 4-space indent, or minify to a single line.

                        

                            
                            

                                
                                
                                
                            

                            

                            

                        

                    

                


                

                    
                        
                            ▸
                            Base64 encode/decode
                        
                        
                    
                    

                        
Both directions — works with multi-byte UTF-8 strings.

                        

                            
                            

                                
                                
                            

                            

                            

                        

                    

                


                

                    
                        
                            ▸
                            Hash generator
                        
                        
                    
                    

                        
Computed via Web Crypto API. SHA-1 is for backward compatibility only; use SHA-256+ for new code.

                        

                            
                            

                                
SHA-1: 

                                
SHA-256: 

                                
SHA-512: 

                            

                        

                    

                

            

        


        

            

                
Backend tools

                
These tools run on our servers (dig, whois, openssl). Rate-limited to 30 requests/min per IP. No logs of what you query — only access logs for the rate limiter. Try them on your own domains or our AS204729.

            


            

                                                        

                        
                            
                                ▸
                                DNS lookup
                            
                            
                        
                        

                            
Resolve a domain. Pick a specific record type or ANY for the bundle.

                            

                                

                                                                            
                                        
                                                                        
                                

                                

                                

                            

                        

                    

                                                        

                        
                            
                                ▸
                                Reverse DNS
                            
                            
                        
                        

                            
What hostname claims a given IP? Works for v4 + v6.

                            

                                

                                                                            
                                                                        
                                

                                

                                

                            

                        

                    

                                                        

                        
                            
                                ▸
                                WHOIS
                            
                            
                        
                        

                            
Registration data for a domain, IP block or AS number. The bulk legalese is stripped so what remains is readable.

                            

                                

                                                                            
                                                                        
                                

                                

                                

                            

                        

                    

                                                        

                        
                            
                                ▸
                                ASN lookup
                            
                            
                        
                        

                            
Which AS number announces this IP? Plus org name, prefix and country. Example: try an IP from our own .

                            

                                

                                                                            
                                                                        
                                

                                

                                

                            

                        

                    

                                                        

                        
                            
                                ▸
                                TLS certificate inspection
                            
                            
                        
                        

                            
Connects to host:port over TLS, dumps the certificate. Shows expiry + days-until-expiry. Requires a real listening TLS endpoint.

                            

                                

                                                                            
                                        
                                                                        
                                

                                

                                

                            

                        

                    

                                                        

                        
                            
                                ▸
                                HTTP header inspection
                            
                            
                        
                        

                            
Fetches headers via HEAD, scores presence of HSTS, CSP, X-Content-Type-Options, X-Frame-Options/frame-ancestors, Referrer-Policy and Permissions-Policy. Private IP ranges blocked (anti-SSRF).

                            

                                

                                                                            
                                                                        
                                

                                

                                

                            

                        

                    

                                                        

                        
                            
                                ▸
                                TCP port check
                            
                            
                        
                        

                            
Tests whether a TCP port is open. Private IP ranges blocked (anti-SSRF). 4-second timeout.

                            

                                

                                                                            
                                        
                                                                        
                                

                                

                                

                            

                        

                    

                            

        


        
            

                
$ ./looking-glass --asn=204729

                
Specific to AS204729: see the Looking Glass

                
ASN and route context for our network, plus external verify links to RIPEstat, bgp.tools, BGPView and PeeringDB.

            

            
                /lookingglass
                            
        

        

            Privacy: all operations happen in your browser via the Web Crypto API. We never see your input. No Google Analytics. No request logs. No cookies (except your session if you're logged in).
Missing a tool? Send a Signal.