diff --git a/README.md b/README.md
index 449ea54..63bb693 100644
--- a/README.md
+++ b/README.md
@@ -81,6 +81,7 @@ document.getElementById("t").innerHTML = this["cipher-collection"].wolfenbuettel
 - AER-256
 - ARMON-64
 - Polybius
+- Bifid
 
 ## 📖 Documentation
 
diff --git a/docs/ciphers/bifid.md b/docs/ciphers/bifid.md
new file mode 100644
index 0000000..d8a0e61
--- /dev/null
+++ b/docs/ciphers/bifid.md
@@ -0,0 +1,64 @@
+# Code code
+
+> The Code code is a code
+
+## Cipher behavior information
+
+* Case sensitive? ✓❌
+* Deterministic? ✓❌
+* Alphabet: **Which alphabet does the cipher use**
+* Characters not in alphabet will be: (**omitted**, **preserved**, **throw an error**, **N/A**)
+
+## Default options object
+
+```
+const options = {
+  optionHere: true // What does this option change
+}
+```
+
+## Usage
+
+### Encoding
+
+#### Default
+
+```
+import { code } from 'cipher-collection'
+
+
+console.log(code.encode('text')) // Result
+```
+
+#### Special case one
+
+```
+import { code } from 'cipher-collection'
+
+const specialOptions = { special: true }
+
+console.log(code.encode('text', specialOptions)) // Special result
+```
+
+
+### Decoding
+
+#### Default
+
+```
+import { code } from 'cipher-collection'
+
+
+console.log(code.decode('ciphertext')) // Cleartext
+```
+
+#### Special case one
+
+```
+import { code } from 'cipher-collection'
+
+const specialOptions = { special: true }
+
+console.log(code.encode('ciphertext', specialOptions)) // Cleartext
+```
+
diff --git a/docs/index.md b/docs/index.md
index bf06e71..7cfef25 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -21,3 +21,4 @@
 * [AER-256](./ciphers/aer256.md)
 * [ARMON-64](./ciphers/armon64.md)
 * [Polybius](./ciphers/polybius.md)
+* [Bifid](./ciphers/bifid.md)
diff --git a/src/bifid.js b/src/bifid.js
new file mode 100644
index 0000000..d9b8202
--- /dev/null
+++ b/src/bifid.js
@@ -0,0 +1,41 @@
+import polybius from './polybius'
+
+const encode = (input, options = {}) => {
+  options = { ...DEFAULT_OPTIONS, ...options }
+  const polybiusNumbers = polybius.encode(input, options).replace(/ /g, '')
+
+  const polybiusNumbersByEvenOdd = Object.values([...polybiusNumbers].reduce((evenOddObj, char, index) => {
+    evenOddObj[isEvenOrOdd(index)] += char
+    return evenOddObj
+  }, { even: '', odd: '' })).join('')
+
+  const separatedPolybiusNumber = polybiusNumbersByEvenOdd.match(/\d{2}/g).join(' ')
+
+  return polybius.decode(separatedPolybiusNumber, options)
+}
+
+const decode = (input, options = {}) => {
+  options = { ...DEFAULT_OPTIONS, ...options }
+  const polybiusNumbers = polybius.encode(input, options).replace(/ /g, '')
+  const numberMiddle = polybiusNumbers.length / 2
+  const splitNumbers = [polybiusNumbers.substr(0, numberMiddle), polybiusNumbers.substr(numberMiddle)]
+
+  const zippedString = Array.from(new Array(numberMiddle)).map((_, i) => splitNumbers[0][i] + splitNumbers[1][i]).join('')
+
+  const separatedPolybiusNumber = zippedString.match(/\d{2}/g).join(' ')
+
+  return polybius.decode(separatedPolybiusNumber, options)
+}
+
+const isEvenOrOdd = i => i % 2 === 0 ? 'even' : 'odd'
+
+const DEFAULT_OPTIONS = {
+  key: '',
+  equalLetters: 'IJ',
+  withNumbers: false
+}
+
+export default {
+  encode,
+  decode
+}
diff --git a/src/index.js b/src/index.js
index f1b1c0c..7bd94eb 100644
--- a/src/index.js
+++ b/src/index.js
@@ -11,6 +11,7 @@ import affine from './affine'
 import aer256 from './aer256'
 import armon64 from './armon64'
 import polybius from './polybius'
+import bifid from './bifid'
 
 export default {
   rot,
@@ -25,5 +26,6 @@ export default {
   affine,
   aer256,
   armon64,
-  polybius
+  polybius,
+  bifid
 }
diff --git a/test/bifid.test.js b/test/bifid.test.js
new file mode 100644
index 0000000..3181030
--- /dev/null
+++ b/test/bifid.test.js
@@ -0,0 +1,65 @@
+import bifid from 'bifid'
+
+describe('encoding', () => {
+  test('default', () => {
+    expect(bifid.encode('ABCDEFGHIJKLMNOPQRSTUVWXYZ')).toBe('AABGGHNNTTUZZBOVHTVHUBOVHU')
+    expect(bifid.encode('ABCDEFGHIJKLMNOPQRSTUVWXYZ'.toLowerCase())).toBe('AABGGHNNTTUZZBOVHTVHUBOVHU')
+  })
+  test('default with illegal character', () => {
+    expect(() => { bifid.encode('*') }).toThrowError('Unknown character *')
+  })
+
+  test('with custom key', () => {
+    expect(bifid.encode('ABCDEFGHIJKLMNOPQRSTUVWXYZ', { key: 'OHA' }))
+      .toBe('OHEDEMMATTUZZNVFRZHNCHNVFU')
+    expect(bifid.encode('ABCDEFGHIJKLMNOPQRSTUVWXYZ', { key: 'oHa' }))
+      .toBe('OHEDEMMATTUZZNVFRZHNCHNVFU')
+  })
+
+  test('with numbers', () => {
+    expect(bifid.encode('ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789', { withNumbers: true }))
+      .toBe('AAAHHHOOOVVV222999BP3BP3BP3BP3BP3BP3')
+  })
+
+  test('with numbers and custom key', () => {
+    expect(bifid.encode('ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789', { withNumbers: true, key: 'oHa' }))
+      .toBe('OOFEFGNANVVV222999P3HMW4GB3HP3HP3HP3')
+  })
+
+  test('with custom substitution', () => {
+    expect(bifid.encode('ABCDEFGHIJKLMNOPQRSTUVWXYZ', { equalLetters: 'UV' }))
+      .toBe('AABGGMMNSSZZZBNUHTBNUHTAHT')
+  })
+})
+
+describe('decoding', () => {
+  test('default', () => {
+    expect(bifid.decode('AABGGHNNTTUZZBOVHTVHUBOVHU')).toBe('ABCDEFGHIIKLMNOPQRSTUVWXYZ')
+  })
+  test('default with illegal character', () => {
+    expect(() => { bifid.decode('*') }).toThrowError('Unknown character *')
+    expect(() => { bifid.decode('88') }).toThrowError('Unknown character 8')
+  })
+
+  test('with custom key', () => {
+    expect(bifid.decode('OHEDEMMATTUZZNVFRZHNCHNVFU', { key: 'OHA' })).toBe('ABCDEFGHIIKLMNOPQRSTUVWXYZ')
+    expect(bifid.decode('OHEDEMMATTUZZNVFRZHNCHNVFU', { key: 'oHa' })).toBe('ABCDEFGHIIKLMNOPQRSTUVWXYZ')
+  })
+
+  test('with numbers', () => {
+    expect(bifid.decode('AAAHHHOOOVVV222999BP3BP3BP3BP3BP3BP3', { withNumbers: true }))
+      .toBe('ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789')
+  })
+
+  test('with numbers and custom key', () => {
+    expect(bifid.decode('OOFEFGNANVVV222999P3HMW4GB3HP3HP3HP3', { withNumbers: true, key: 'oHa' }))
+      .toBe('ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789')
+  })
+
+  test('with custom substitution', () => {
+    expect(bifid.decode('AABGGMMNSSZZZBNUHTBNUHTAHT', { equalLetters: 'UV' }))
+      .toBe('ABCDEFGHIJKLMNOPQRSTUUWXYZ')
+    expect(bifid.decode('AABGGMMNSSZZZBNUHTBNUHTAHT', { equalLetters: 'VU' }))
+      .toBe('ABCDEFGHIJKLMNOPQRSTVVWXYZ')
+  })
+})