Developer Utilities
Small developer utilities that save a trip to a random website. Encode and decode Base64, explain a regex, build UTM links, generate QR codes and vCards, and more — the everyday helpers. Free in your browser, and available by API when you need them in a script.
Population count (popcount) calculator
Count how many ones a number has in binary: 42 written in 8 bits is 00101010, with 3 ones at positions 1, 3 and 5 and 5 zeros.
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Arithmetic right shift calculator
At 8 bits, −42 shifted right by 3 gives −6: the pattern 11010110 becomes 11111010 because the sign bit is copied into the freed places.
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Bit mask generator
Four consecutive ones starting at bit 0 make the mask 15: 0b1111 in binary and 0xf in hex. Give the width and, if needed, the lowest bit position, and get the…
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Bitmask flags decoder
With read (1), write (2), execute (4) and admin (8), the value 13 decodes to read, execute and admin, with nothing left unexplained.
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Byte array to integer calculator
The bytes 0, 1, 2, 3 read big-endian make 66051, hex 0x00010203; read little-endian they make 50462976.
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Hamming Distance Between Integers Calculator
Enter two whole numbers and get their Hamming distance: 29 and 15 differ in 2 bit positions, because their XOR is 18, or 10010 in binary.
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Highest set bit position calculator
13 is 1101 in binary, so its highest set bit sits at position 3, with a bit length of 4 and 8 as the largest power of two that does not exceed it.
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Test bit at position calculator
42 is 101010 in binary, so the bit at position 3, worth 8, is set: enter a whole number and a position counted from 0 on the right to get a yes-or-no answer and…
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Unsigned to signed integer calculator
255 in 8 bits is all ones, so read as a signed number it becomes −1: enter an unsigned value and a width from 2 to 53 bits to get its two's-complement reading…
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Bit Length of Integer Calculator
18446744073709551615 needs exactly 64 bits, and decimal 13, binary 1101, needs 4. Type any non-negative whole number, however long, and get the minimum count of…
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Double-precision float to bits
See exactly how a computer stores a decimal as a 64-bit double: 1 becomes 3FF0000000000000, with sign bit 0, exponent 1023 and 52 zero mantissa bits.
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Morton Code Decoder
Enter one Morton number and get back the two coordinates packed inside it: 39 decodes to x 3 and y 5.
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Saturating integer add calculator
Add two integers and keep the sum inside a fixed bit width: 100 + 50 in a signed 8-bit word gives 127 instead of wrapping to a negative number, with the exact…
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Fractional base converter
Decimal 0.1 is 0.0(0011) in binary: a cycle of 4 digits that repeats forever, not a rounded bit. Convert any fraction between bases 2 and 16, with the repeating…
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CIDR usable hosts calculator
192.168.1.37/24 belongs to 192.168.1.0/24, a block of 256 addresses with 254 usable hosts once the network and broadcast are reserved.
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CIDR prefix to subnet mask converter
/24 becomes subnet mask 255.255.255.0 and wildcard mask 0.0.0.255, covering 256 addresses. Enter any IPv4 prefix length from 0 to 32 and get the dotted-decimal…
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IPv4 address class calculator
Type an IPv4 address and get its classful category from the first octet: 192.168.1.10 is class C, with leading bits 110, default mask 255.255.255.0 and the…
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IPv4 to hexadecimal converter
Turn a dotted IPv4 address into hex and binary, octet by octet: 192.168.1.10 becomes C0.A8.01.0A, or C0A8010A in one piece, and…
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LEB128 Varint Decoder
Decode an unsigned LEB128 varint into its exact number: the bytes E5 8E 26 give 624485. Paste hex or decimal bytes, and incomplete or overlong sequences are…
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Prefix length to address count calculator
An IPv4 /24 holds 256 addresses and an IPv6 /64 exactly 18,446,744,073,709,551,616. Choose the address family, enter the number after the slash and get the…
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IP range to CIDR calculator
Enter a first and last IPv4 address and get the fewest CIDR blocks that cover exactly that range: 192.168.1.13 to 192.168.1.20 becomes four blocks, with no…
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IPv4-mapped IPv6 converter
Enter 192.0.2.1 and get every common way to write it inside IPv6: ::ffff:192.0.2.1 and ::ffff:c000:201 for the mapped form, ::192.0.2.1 and ::c000:201 for the…
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IPv6 address expander
Paste a shortened IPv6 address and get its full form: 2001:db8::1 expands to 2001:0db8:0000:0000:0000:0000:0000:0001, with every zero group restored and each of…
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IPv6 prefix checker
See at once whether an IPv6 address falls inside a prefix, such as 2001:db8:1234:abcd::42 inside 2001:db8:1234::/48, along with the block's first and last…
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Next or previous IP address calculator
Get the IPv4 address one step ahead or one step behind: after 192.168.0.255 comes 192.168.1.0, never an impossible 256.
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Complexity crossover point calculator
With 1·n² against 10·n log n, the quadratic algorithm stays cheaper until n reaches 59, where the n log n one takes over.
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IP address version detector
Paste an address and learn whether it is a complete IPv4, a complete IPv6 or neither: 192.168.1.42 comes back as valid IPv4.
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Linear Search Average Comparisons Calculator
Find how many comparisons a linear search makes on average when the target is present: with 100 elements it is 50.5, from the formula (n + 1) / 2, and the worst…
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MAC address type analyzer
Paste a MAC address and see what its first octet says: 02:42:AC:11:00:02 starts with 00000010 in binary, so it is unicast and locally administered.
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Merge Sort Comparisons Calculator
See how many comparisons merge sort really makes: 8 elements need at most 17 and 15.733333 on average across 3 merge levels, while the familiar n log2 n gives…
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TCP window size for throughput
100 Mbps over a 50 ms round trip needs 625,000 bytes in flight, far beyond the classic 65,535-byte TCP window: enter your target speed and RTT to get the window…
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WiFi channel frequency calculator for 2.4 GHz and 5 GHz
Channel 6 in the 2.4 GHz band is centered on 2437 MHz and channel 11 on 2462 MHz: 25 MHz apart, with no shared spectrum.
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Amdahl's Law Speedup Calculator
With 95% parallel work, 16 processors speed a job up just over 9 times, not 16, and nearly half of the new runtime is still serial.
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Hash bits for collision resistance
Storing 1,000,000 items with at most a one-in-a-million chance of any collision takes 59 bits of hash, the smallest width that meets the birthday bound.
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Hash table load factor calculator
Enter 600 items in 800 buckets and get a load factor of 0.75, or 75%: at the default 0.75 threshold a resize is advised, and 801 buckets is the minimum to drop…
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Binary Heap Children Index Calculator
Enter a node's index and choose the numbering: in a zero-based heap, node 5 has its children at 11 and 12, from the rules 2i + 1 and 2i + 2.
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Huffman code length calculator
Enter the frequencies 5, 9, 12, 13, 16 and 45 and get optimal Huffman code lengths of 4, 4, 3, 3, 3 and 1: 224 bits in total and 2.24 bits per symbol on…
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Recursion tree node count calculator
Count the nodes of a divide-and-conquer recursion tree level by level: two half-size subproblems starting from 16 give 5 levels of 1, 2, 4, 8 and 16 nodes, 31…
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Required operations per second calculator
Work out the throughput a job needs to finish on time: 2,500,000 operations in five seconds need 500,000 operations per second.
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Row-major array index calculator
In a 3 × 4 × 5 array of 8-byte elements, position 1, 2, 3 is element 33, byte offset 264, address 4360 from a base of 4096.
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Balanced brackets validator
Paste code or text and see at once whether every (, [ and { closes in the right order: ({[]}) passes, ([)] fails, and the first mismatch is pinpointed with its…
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Binary tree max nodes calculator
A perfect binary tree of height 3 holds 15 nodes, 8 of them leaves, with 1, 2, 4 and 8 nodes on its four levels.
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Code comment line counter
Measure how much of a source file explains rather than runs: a six-line snippet with three comment lines and three code lines gives a ratio of 1, with comments…
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Struct field offset calculator
A char, an int and a char take 12 bytes, not 6: this calculator shows each member's offset, the padding before it and the trailing padding, with the same rules…
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Requests per second to daily converter for traffic planning
Put one steady traffic rate on every clock at once: 125 requests per second is 7,500 per minute, 450,000 per hour and 10,800,000 per day.
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Servers needed for load calculator
Turn a traffic peak into a server count: 10,000 requests per second on servers that handle 1,200 each, with 25 % kept in reserve, needs 12 servers, because each…
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Batch throughput calculator
A batch of 500 items every 20 seconds sustains 25 items per second, 1,500 per minute and 90,000 per hour.
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RAID capacity calculator
See how much space a RAID array really leaves you and how many disks it can lose: four 1000 GB disks in RAID 5 give 3000 GB usable, 75% efficiency and survive…
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SemVer range satisfies checker
Check whether a version falls inside a range, as when 2.4.1+build.7 satisfies 1.8.x || >=2.0.0 <3.0.0 through the second alternative.
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Token bucket rate limit calculator
A bucket of 10 tokens holding 5 and refilling at 2 per second has 8 ready after 1.5 seconds, so a burst of 3 goes through and leaves 5.
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Glob pattern to regex converter
Paste a glob and get the matching regular expression: *.js becomes ^.*\.js$, with the dot escaped so it only matches a real dot.
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Key Length to Keyspace Calculator
Turn a key length into the exact number of possible keys: a 56-bit key has 72,057,594,037,927,936, and a 128-bit key has 2 to the power 72 times as many.
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Rendezvous hashing node selector
Assign a key to one node from your list: user:42 across cache-a, cache-b and cache-c lands on cache-a, and stays there until the node list or the seed changes.
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Umask calculator
With umask 022, new files get 644 (rw-r--r--) and new folders get 755 (rwxr-xr-x): enter any umask to see the default permissions it produces, in octal and rwx…
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UUID format validator
550E8400-E29B-41D4-A716-446655440000 is valid, version 4 with the RFC 4122 variant, and comes back in lowercase canonical form: paste a UUID to check its…
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Hamming ECC parity bits calculator
Find the fewest parity bits a Hamming code needs for your data: 4 data bits need 3, giving the classic (7,4) code with no spare syndromes.
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Fenwick tree index calculator
Type an index and see how a Fenwick tree moves from it: index 13 is 1101 in binary, its lowest set bit is 1, the update step goes to 14 and the query step to…
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IPv6 to binary converter
See all 128 bits behind an IPv6 address such as 2001:db8::1, expanded to eight groups of sixteen bits that start with 0010000000000001, with every leading zero…
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Count leading zeros calculator
Count the zero bits above the highest one-bit of a number in a fixed-width word: 16 in 8 bits is 00010000, so the count is 3.
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Byte-order swap calculator
0x12345678 becomes 0x78563412 when its four bytes are reversed, the step between network order and little-endian memory.
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