Best Free Online Developer Tools to Use in 2026
A practical, opinionated list of the best free online developer tools worth using in 2026, organized by category so you can find what you need fast.
Aug 08, 2026
IPv4 to IPv6 Converter
Convert IPv4 addresses to IPv6 mapped and compatible notation, or extract embedded IPv4 addresses from IPv6.
Enter a standard IPv4 address to convert to IPv6 notation.
IPv6 Mapped
::ffff:192.168.1.1
Standard IPv6 representation of IPv4 — ::ffff:0:0/96 prefix
IPv6 Compatible
::192.168.1.1
IPv4-compatible IPv6 address — ::/96 prefix (deprecated but still used)
Full IPv6 (hex)
0000:0000:0000:0000:0000:ffff:c0a8:0101
Full 128-bit IPv6 address in hexadecimal notation
IPv4
-
Hex (IPv4 octets)
-
IPv4 Decimal
-
Enter an IPv6 address with embedded IPv4 (mapped or compatible notation) to extract the IPv4 address.
Extracted IPv4
192.168.1.1
Type
-
IPv6 Prefix
-
Full IPv6 (hex)
-
No embedded IPv4 address found
This IPv6 address does not contain an embedded IPv4 address. It may be a native IPv6 address or use a different format.
- Choose a direction — Select IPv4 → IPv6 to convert an IPv4 address to IPv6 notation, or IPv6 → IPv4 to extract an embedded IPv4 address from an IPv6 address.
- Enter the address — Type or paste an IPv4 address (e.g.,
192.168.1.1) or an IPv6 address with embedded IPv4 (e.g.,::ffff:192.168.1.1). - View results — The converted addresses appear in real-time with IPv6 mapped, compatible, and full hex notation.
All conversion is performed 100% client-side in your browser. No data is sent to any server.
What Is IPv4 to IPv6 Mapping?
IPv4 to IPv6 mapping is a technique for representing IPv4 addresses within the IPv6 address space. There are two primary methods:
- IPv6 Mapped (
::ffff:0:0/96) — The standard mechanism for representing IPv4 addresses in IPv6, used by modern operating systems for dual-stack communication. Format:::ffff:x.x.x.x - IPv6 Compatible (
::/96) — An older technique for IPv6 transition, now deprecated but still encountered. Format:::x.x.x.x
These mappings allow applications and systems using IPv6 sockets to communicate with IPv4 hosts transparently, forming the basis of IPv6 transition technologies.
Conversion Examples
| IPv4 | IPv6 Mapped | IPv6 Compatible | Full Hex |
|---|---|---|---|
| 127.0.0.1 | ::ffff:127.0.0.1 | ::7f00:1 | 0000:0000:0000:0000:0000:ffff:7f00:0001 |
| 192.168.1.1 | ::ffff:192.168.1.1 | ::c0a8:101 | 0000:0000:0000:0000:0000:ffff:c0a8:0101 |
| 10.0.0.1 | ::ffff:10.0.0.1 | ::a00:1 | 0000:0000:0000:0000:0000:ffff:0a00:0001 |
| 172.16.0.1 | ::ffff:172.16.0.1 | ::ac10:1 | 0000:0000:0000:0000:0000:ffff:ac10:0001 |
| 8.8.8.8 | ::ffff:8.8.8.8 | ::808:808 | 0000:0000:0000:0000:0000:ffff:0808:0808 |
What is an IPv4-mapped IPv6 address?
An IPv4-mapped IPv6 address is an IPv6 address that embeds an IPv4 address in the lower 32 bits with a prefix of ::ffff:0:0/96 (80 zero bits + 16 bits of ones). It is used by dual-stack systems to represent IPv4 addresses in an IPv6 socket API.
What is the difference between mapped and compatible?
IPv6 Mapped (::ffff:0:0/96) inserts 16 bits of ffff between the zero prefix and the IPv4 address. IPv6 Compatible (::/96) is simply 96 zero bits followed by the IPv4 address. The mapped format is the modern standard; compatible was used in early IPv6 transition but has been deprecated.
How do I detect an embedded IPv4 in an IPv6 address?
Look for the ::ffff: prefix (IPv4-mapped) or :: followed by a dotted decimal notation. The last 32 bits (8 hex digits or 4 decimal octets) contain the IPv4 address. The tool automatically detects both mapped and compatible formats.
Why does my system use IPv4-mapped IPv6 addresses?
Modern operating systems use IPv4-mapped IPv6 addresses to enable seamless dual-stack operation. When an application binds to an IPv6 socket, it can accept connections from both IPv4 and IPv6 clients. IPv4 connections appear as IPv4-mapped IPv6 addresses (::ffff:x.x.x.x) in the socket API.
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