Free IP Address & ASN Lookup Tool
Validate and analyze IPv4 and IPv6 addresses instantly. Detect private ranges (RFC1918), lookup ASN (Autonomous System Numbers), and identify organization ownership. 100% Private – IP validation happens locally; ASN lookups are optional.
ASN lookup uses IPInfo if `NEXT_PUBLIC_IPINFO_TOKEN` is set.
Result
Lookup results will appear here.
What is IP/ASN Lookup?
An IP/ASN Lookup tool is a specialized utility that validates and analyzes IP addresses while providing detailed network ownership information. Our free online tool validates both IPv4 and IPv6 addresses, detects private IP ranges (RFC1918, loopback, link-local), and optionally enriches results with ASN (Autonomous System Number) data including organization ownership and country information.
Unlike server-based tools, our IP validator performs 100% client-side parsing using the ipaddr.js library, ensuring your IP addresses never leave your browser during validation. ASN lookup is completely optional and only makes external API calls to IPInfo when you have a token configured. This privacy-first architecture makes our tool ideal for security-conscious users, network administrators, and developers who need to validate IPs without exposing sensitive infrastructure information.
Whether you're troubleshooting network connectivity, analyzing server logs, implementing IP-based access control, or conducting security audits, our IP/ASN Lookup tool provides instant validation with detailed breakdown of IP components, CIDR notation, private range detection, and comprehensive network ownership data. The tool supports all standard IPv4 formats (dotted decimal) and IPv6 formats (compressed and expanded notation), automatically normalizing addresses to standard CIDR format for consistency.
Key Features of Our IP/ASN Lookup Tool
IPv4 & IPv6 Support
Validate both IPv4 (32-bit) and IPv6 (128-bit) addresses with automatic format detection and normalization.
Private Range Detection
Automatically identifies RFC1918 private addresses, loopback, link-local, and other reserved ranges.
ASN Lookup
Retrieve Autonomous System Numbers, organization names, ISP information, and country data.
CIDR Notation
Display normalized IP addresses in standard CIDR format for consistency and clarity.
100% Client-Side Parsing
IP validation happens entirely in your browser using ipaddr.js—no server uploads required.
Export & Copy
Copy individual fields or download complete results as JSON or CSV for further analysis.
No Rate Limits
Validate unlimited IP addresses without restrictions—basic parsing works offline.
Privacy-First Design
Your IP addresses are never logged or stored. ASN lookups are optional and user-controlled.
Sample IPs Included
Quick-start samples for IPv4, IPv6, and private addresses to test functionality instantly.
Common Use Cases for IP/ASN Lookup
Network Security & Analysis
- •Identify suspicious IP addresses in server logs and security events
- •Validate IP addresses before adding to firewall rules or blacklists
- •Determine network ownership and ASN for threat intelligence analysis
- •Detect private IP leakage in public-facing configurations
Server & Infrastructure Management
- •Verify DNS resolution results and reverse DNS lookups
- •Troubleshoot network connectivity and routing issues
- •Document server IPs with ASN and organization information
- •Validate IP address assignments in multi-cloud environments
API Development & Testing
- •Implement IP-based rate limiting and access control
- •Validate user-submitted IP addresses in forms and APIs
- •Test geolocation features with known country-specific IPs
- •Debug webhook origins and API request sources
Debugging & Diagnostics
- •Analyze application logs to identify request origins
- •Verify CDN and proxy IP addresses in X-Forwarded-For headers
- •Understand IPv6 address allocation and subnetting
- •Validate network configuration during infrastructure changes
Understanding IP Addresses: IPv4 vs IPv6
Internet Protocol version 4
Format: 32-bit addresses represented as four decimal octets (0-255) separated by dots.
Example: 192.168.1.1, 8.8.8.8
Address Space: Approximately 4.3 billion addresses (2³² = 4,294,967,296)
Private Ranges (RFC1918):
- •
10.0.0.0/8(10.0.0.0 – 10.255.255.255) - •
172.16.0.0/12(172.16.0.0 – 172.31.255.255) - •
192.168.0.0/16(192.168.0.0 – 192.168.255.255)
Status: Address exhaustion reached in 2011. NAT (Network Address Translation) extends usability.
Internet Protocol version 6
Format: 128-bit addresses represented as eight groups of four hexadecimal digits separated by colons.
Example: 2001:4860:4860::8888
Address Space: Approximately 340 undecillion addresses (2¹²⁸ ≈ 3.4 × 10³⁸)
Private Ranges:
- •
fc00::/7(Unique Local Addresses) - •
fe80::/10(Link-Local Addresses) - •
::1/128(Loopback)
Status: Designed to solve IPv4 exhaustion. Adoption growing steadily worldwide.
Note on Compressed Notation: IPv6 addresses can omit leading zeros in each group and replace consecutive groups of zeros with :: (can only be used once). For example, 2001:0db8:0000:0000:0000:0000:0000:0001 becomes 2001:db8::1. Our tool automatically normalizes these formats.
What is an ASN (Autonomous System Number)?
An Autonomous System Number (ASN) is a unique identifier assigned to an autonomous system (AS) on the internet. An autonomous system is a collection of IP networks and routers under the control of a single organization that presents a common routing policy to the internet. ASNs are essential for Border Gateway Protocol (BGP) routing, which enables different networks to exchange routing information and direct traffic across the internet.
ASN Examples & Common Organizations
AS15169 - Google LLC
Google's primary ASN, routing traffic for Google Search, YouTube, Gmail, and other services.
AS13335 - Cloudflare
Cloudflare's global CDN and DDoS protection network spanning 300+ cities.
AS16509 - Amazon.com
Amazon Web Services (AWS) infrastructure powering millions of applications.
AS8075 - Microsoft
Microsoft's Azure cloud platform and enterprise services network.
Why ASN Lookup Matters
- ✓Network Identification: Determine which organization owns and operates an IP address
- ✓Security Analysis: Identify the origin of suspicious traffic, attacks, or abuse
- ✓Routing Intelligence: Understand network paths and peering relationships
- ✓Compliance & Auditing: Verify cloud provider infrastructure and data residency
Our IP/ASN Lookup tool retrieves ASN information via the IPInfo API when configured, providing organization names, country data, and network ownership details to help you understand who controls an IP address and where it's located geographically.
Why Use Our IP/ASN Lookup Tool?
Privacy-First Architecture
Unlike many IP lookup tools that log and track every query, our tool performs validation 100% locally in your browser. Your IP addresses are never sent to our servers for basic validation. ASN enrichment is completely optional and user-controlled, ensuring you maintain full control over your data. Perfect for security-conscious organizations validating internal infrastructure IPs.
No Limits, Always Free
No registration, no rate limits, no hidden costs. Validate unlimited IP addresses without restrictions. Whether you're analyzing 10 IPs or 10,000, our tool remains fast and responsive. Basic IP validation works completely offline, and ASN lookup uses your own IPInfo token (free tier: 50,000 requests/month), giving you full control over usage and costs.
Developer-Friendly Output
Export results as JSON or CSV for integration with your workflows. Copy individual fields with one click, or download complete datasets for bulk analysis. Results include all essential information: IP version, private range detection, CIDR notation, ASN details, organization name, and country—formatted consistently for easy parsing and automation.
Frequently Asked Questions
Is this IP lookup tool completely free?▼
Yes, our IP/ASN Lookup tool is 100% free with no limitations on basic IP validation. You can validate unlimited IPv4 and IPv6 addresses without any subscription or payment. ASN enrichment (organization, country data) requires an IPInfo token, but IPInfo offers a generous free tier with 50,000 requests per month, which is sufficient for most use cases.
Does this tool send my IP addresses to your servers?▼
No, basic IP validation happens 100% locally in your browser using the ipaddr.js library. Your IP addresses are never sent to our servers during validation. ASN lookups are optional and make direct API calls from your browser to IPInfo (not through our servers) only when you have configured a token and clicked the Lookup button.
What IP address formats are supported?▼
The tool supports all standard IPv4 formats (dotted decimal notation like 192.168.1.1) and IPv6 formats including expanded notation (2001:0db8:0000:0000:0000:0000:0000:0001), compressed notation (2001:db8::1), and mixed formats. IPv6 addresses are automatically normalized to standard CIDR format for consistency.
How does private IP detection work?▼
Our tool uses ipaddr.js to detect all reserved and private IP ranges including RFC1918 private addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), loopback addresses (127.0.0.0/8, ::1/128), link-local addresses (169.254.0.0/16, fe80::/10), multicast, and other IETF-reserved ranges. Private IPs are flagged immediately during validation.
Do I need an IPInfo token for basic IP validation?▼
No, an IPInfo token is only required if you want ASN enrichment data (Autonomous System Number, organization name, ISP, country). Without a token, the tool still validates IP addresses, detects private ranges, shows IP version (IPv4/IPv6), and displays normalized CIDR format—all locally in your browser without any API calls.
Can I lookup multiple IP addresses at once?▼
Currently, the tool validates one IP address at a time for optimal user experience and performance. Bulk IP lookup functionality with CSV input/output is planned for a future version (v1.3) based on user feedback. For now, you can validate IPs sequentially and export each result as JSON or CSV for aggregation.
What is the difference between IPv4 and IPv6?▼
IPv4 uses 32-bit addresses (4 octets like 192.168.1.1) supporting approximately 4.3 billion addresses, while IPv6 uses 128-bit addresses (8 groups of hexadecimal digits like 2001:4860:4860::8888) supporting 340 undecillion addresses. IPv6 was designed to solve IPv4 address exhaustion and includes built-in security features. Our tool validates and normalizes both formats.
How accurate is the ASN and geolocation data?▼
ASN data from IPInfo is highly accurate (99%+) as it's sourced directly from Regional Internet Registries (RIRs) and BGP routing tables. Organization names and ASN assignments are authoritative. Country-level geolocation is typically 95-99% accurate. However, IP addresses can be reassigned, and some organizations use anycast routing where the same IP serves multiple geographic locations.
How to Use the IP/ASN Lookup Tool
- 1
Enter an IP address
Type or paste any IPv4 address (e.g., 8.8.8.8, 192.168.1.1) or IPv6 address (e.g., 2001:4860:4860::8888) into the input field. You can also click one of the sample buttons to quickly load example IPs: public IPv4, public IPv6, or private address.
- 2
Click the Lookup button
Click "Lookup" to validate the IP address. The tool will immediately parse the IP locally in your browser, detect its version (IPv4/IPv6), identify if it's a private range, and show the normalized CIDR format. If you have an IPInfo token configured via
NEXT_PUBLIC_IPINFO_TOKEN, the tool will also fetch ASN data. - 3
Review the results
The results panel displays all available information: IP address, version (IPv4/IPv6), private range status (Yes/No), normalized CIDR notation, and optional ASN enrichment data (ASN number, organization name, country). Each field is clearly labeled for easy interpretation.
- 4
Copy or export data
Click the copy button next to any field to copy its value to your clipboard. Use "Copy JSON" to copy the entire result as formatted JSON, or click the download buttons to save results as JSON or CSV files for further analysis, documentation, or integration with other tools.