diff --git a/README.md b/README.md
index f8374e6..a466219 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,24 @@ yarn add @neaps/tide-prediction
 
 ```
 
+## Importing
+
+Using Ecmascript Imports:
+
+```js
+import TidePrediction from '@neaps/tide-prediction'
+```
+
+Using CommonJS
+
+```js
+const TidePrediction = require('@neaps/tide-prediction')
+
+// Before NodeJS version with conditional export support
+
+const TidePrediction = require('@neaps/tide-prediction/dist/commonjs')
+```
+
 # Usage
 
 Neaps requires that you [provide your own tidal harmonics information](#constituent-object) to generate a prediction.
@@ -35,6 +53,7 @@ Note that, for now, Neaps **will not** do any timezone corrections. This means y
 
 ```javascript
 import TidePrediction from '@neaps/tide-prediction'
+
 const constituents = [
   {
     phase_GMT: 98.7,
diff --git a/dist/commonjs/index.js b/dist/commonjs/index.js
new file mode 100644
index 0000000..fb9422e
--- /dev/null
+++ b/dist/commonjs/index.js
@@ -0,0 +1,1005 @@
+'use strict';
+
+const d2r = Math.PI / 180.0;
+const r2d = 180.0 / Math.PI;
+
+// Convert a sexagesimal angle into decimal degrees
+const sexagesimalToDecimal = (degrees, arcmins, arcsecs, mas, muas) => {
+  arcmins = typeof arcmins !== 'undefined' ? arcmins : 0;
+  arcsecs = typeof arcsecs !== 'undefined' ? arcsecs : 0;
+  mas = typeof mas !== 'undefined' ? mas : 0;
+  muas = typeof muas !== 'undefined' ? muas : 0;
+
+  return (
+    degrees +
+    arcmins / 60.0 +
+    arcsecs / (60.0 * 60.0) +
+    mas / (60.0 * 60.0 * 1e3) +
+    muas / (60.0 * 60.0 * 1e6)
+  )
+};
+
+const coefficients = {
+  // Meeus formula 21.3
+  terrestrialObliquity: [
+    sexagesimalToDecimal(23, 26, 21.448),
+    -sexagesimalToDecimal(0, 0, 4680.93),
+    -sexagesimalToDecimal(0, 0, 1.55),
+    sexagesimalToDecimal(0, 0, 1999.25),
+    -sexagesimalToDecimal(0, 0, 51.38),
+    -sexagesimalToDecimal(0, 0, 249.67),
+    -sexagesimalToDecimal(0, 0, 39.05),
+    sexagesimalToDecimal(0, 0, 7.12),
+    sexagesimalToDecimal(0, 0, 27.87),
+    sexagesimalToDecimal(0, 0, 5.79),
+    sexagesimalToDecimal(0, 0, 2.45),
+  ].map((number, index) => {
+    return number * Math.pow(1e-2, index)
+  }),
+
+  solarPerigee: [
+    280.46645 - 357.5291,
+    36000.76932 - 35999.0503,
+    0.0003032 + 0.0001559,
+    0.00000048,
+  ],
+
+  solarLongitude: [280.46645, 36000.76983, 0.0003032],
+
+  lunarInclination: [5.145],
+
+  lunarLongitude: [
+    218.3164591,
+    481267.88134236,
+    -0.0013268,
+    1 / 538841.0 - 1 / 65194000.0,
+  ],
+
+  lunarNode: [
+    125.044555,
+    -1934.1361849,
+    0.0020762,
+    1 / 467410.0,
+    -1 / 60616000.0,
+  ],
+
+  lunarPerigee: [
+    83.353243,
+    4069.0137111,
+    -0.0103238,
+    -1 / 80053.0,
+    1 / 18999000.0,
+  ],
+};
+
+// Evaluates a polynomial at argument
+const polynomial = (coefficients, argument) => {
+  const result = [];
+  coefficients.forEach((coefficient, index) => {
+    result.push(coefficient * Math.pow(argument, index));
+  });
+  return result.reduce((a, b) => {
+    return a + b
+  })
+};
+
+// Evaluates a derivative polynomial at argument
+const derivativePolynomial = (coefficients, argument) => {
+  const result = [];
+  coefficients.forEach((coefficient, index) => {
+    result.push(coefficient * index * Math.pow(argument, index - 1));
+  });
+  return result.reduce((a, b) => {
+    return a + b
+  })
+};
+
+// Meeus formula 11.1
+const T = (t) => {
+  return (JD(t) - 2451545.0) / 36525
+};
+
+// Meeus formula 7.1
+const JD = (t) => {
+  let Y = t.getFullYear();
+  let M = t.getMonth() + 1;
+  const D =
+    t.getDate() +
+    t.getHours() / 24.0 +
+    t.getMinutes() / (24.0 * 60.0) +
+    t.getSeconds() / (24.0 * 60.0 * 60.0) +
+    t.getMilliseconds() / (24.0 * 60.0 * 60.0 * 1e6);
+  if (M <= 2) {
+    Y = Y - 1;
+    M = M + 12;
+  }
+  const A = Math.floor(Y / 100.0);
+  const B = 2 - A + Math.floor(A / 4.0);
+  return (
+    Math.floor(365.25 * (Y + 4716)) +
+    Math.floor(30.6001 * (M + 1)) +
+    D +
+    B -
+    1524.5
+  )
+};
+
+/**
+ * @todo - What's  with the array returned from the arccos?
+ * @param {*} N
+ * @param {*} i
+ * @param {*} omega
+ */
+const _I = (N, i, omega) => {
+  N = d2r * N;
+  i = d2r * i;
+  omega = d2r * omega;
+  const cosI =
+    Math.cos(i) * Math.cos(omega) - Math.sin(i) * Math.sin(omega) * Math.cos(N);
+  return r2d * Math.acos(cosI)
+};
+
+const _xi = (N, i, omega) => {
+  N = d2r * N;
+  i = d2r * i;
+  omega = d2r * omega;
+  let e1 =
+    (Math.cos(0.5 * (omega - i)) / Math.cos(0.5 * (omega + i))) *
+    Math.tan(0.5 * N);
+  let e2 =
+    (Math.sin(0.5 * (omega - i)) / Math.sin(0.5 * (omega + i))) *
+    Math.tan(0.5 * N);
+  e1 = Math.atan(e1);
+  e2 = Math.atan(e2);
+  e1 = e1 - 0.5 * N;
+  e2 = e2 - 0.5 * N;
+  return -(e1 + e2) * r2d
+};
+
+const _nu = (N, i, omega) => {
+  N = d2r * N;
+  i = d2r * i;
+  omega = d2r * omega;
+  let e1 =
+    (Math.cos(0.5 * (omega - i)) / Math.cos(0.5 * (omega + i))) *
+    Math.tan(0.5 * N);
+  let e2 =
+    (Math.sin(0.5 * (omega - i)) / Math.sin(0.5 * (omega + i))) *
+    Math.tan(0.5 * N);
+  e1 = Math.atan(e1);
+  e2 = Math.atan(e2);
+  e1 = e1 - 0.5 * N;
+  e2 = e2 - 0.5 * N;
+  return (e1 - e2) * r2d
+};
+
+// Schureman equation 224
+const _nup = (N, i, omega) => {
+  const I = d2r * _I(N, i, omega);
+  const nu = d2r * _nu(N, i, omega);
+  return (
+    r2d *
+    Math.atan(
+      (Math.sin(2 * I) * Math.sin(nu)) /
+        (Math.sin(2 * I) * Math.cos(nu) + 0.3347)
+    )
+  )
+};
+
+// Schureman equation 232
+const _nupp = (N, i, omega) => {
+  const I = d2r * _I(N, i, omega);
+  const nu = d2r * _nu(N, i, omega);
+  const tan2nupp =
+    (Math.sin(I) ** 2 * Math.sin(2 * nu)) /
+    (Math.sin(I) ** 2 * Math.cos(2 * nu) + 0.0727);
+  return r2d * 0.5 * Math.atan(tan2nupp)
+};
+
+const modulus$1 = (a, b) => {
+  return ((a % b) + b) % b
+};
+
+const astro = (time) => {
+  const result = {};
+  const polynomials = {
+    s: coefficients.lunarLongitude,
+    h: coefficients.solarLongitude,
+    p: coefficients.lunarPerigee,
+    N: coefficients.lunarNode,
+    pp: coefficients.solarPerigee,
+    90: [90.0],
+    omega: coefficients.terrestrialObliquity,
+    i: coefficients.lunarInclination
+  };
+
+  // Polynomials are in T, that is Julian Centuries; we want our speeds to be
+  // in the more convenient unit of degrees per hour.
+  const dTdHour = 1 / (24 * 365.25 * 100);
+  Object.keys(polynomials).forEach((name) => {
+    result[name] = {
+      value: modulus$1(polynomial(polynomials[name], T(time)), 360.0),
+      speed: derivativePolynomial(polynomials[name], T(time)) * dTdHour
+    };
+  });
+
+  // Some other parameters defined by Schureman which are dependent on the
+  // parameters N, i, omega for use in node factor calculations. We don't need
+  // their speeds.
+  const functions = {
+    I: _I,
+    xi: _xi,
+    nu: _nu,
+    nup: _nup,
+    nupp: _nupp
+  };
+  Object.keys(functions).forEach((name) => {
+    const functionCall = functions[name];
+    result[name] = {
+      value: modulus$1(
+        functionCall(result.N.value, result.i.value, result.omega.value),
+        360.0
+      ),
+      speed: null
+    };
+  });
+
+  // We don't work directly with the T (hours) parameter, instead our spanning
+  // set for equilibrium arguments #is given by T+h-s, s, h, p, N, pp, 90.
+  // This is in line with convention.
+  const hour = {
+    value: (JD(time) - Math.floor(JD(time))) * 360.0,
+    speed: 15.0
+  };
+
+  result['T+h-s'] = {
+    value: hour.value + result.h.value - result.s.value,
+    speed: hour.speed + result.h.speed - result.s.speed
+  };
+
+  // It is convenient to calculate Schureman's P here since several node
+  // factors need it, although it could be argued that these
+  // (along with I, xi, nu etc) belong somewhere else.
+  result.P = {
+    value: result.p.value - (result.xi.value % 360.0),
+    speed: null
+  };
+
+  return result
+};
+
+const modulus = (a, b) => {
+  return ((a % b) + b) % b
+};
+
+const addExtremesOffsets = (extreme, offsets) => {
+  if (typeof offsets === 'undefined' || !offsets) {
+    return extreme
+  }
+  if (extreme.high && offsets.height_offset && offsets.height_offset.high) {
+    extreme.level *= offsets.height_offset.high;
+  }
+  if (extreme.low && offsets.height_offset && offsets.height_offset.low) {
+    extreme.level *= offsets.height_offset.low;
+  }
+  if (extreme.high && offsets.time_offset && offsets.time_offset.high) {
+    extreme.time = new Date(
+      extreme.time.getTime() + offsets.time_offset.high * 60 * 1000
+    );
+  }
+  if (extreme.low && offsets.time_offset && offsets.time_offset.low) {
+    extreme.time = new Date(
+      extreme.time.getTime() + offsets.time_offset.low * 60 * 1000
+    );
+  }
+  return extreme
+};
+
+const getExtremeLabel = (label, highLowLabels) => {
+  if (
+    typeof highLowLabels !== 'undefined' &&
+    typeof highLowLabels[label] !== 'undefined'
+  ) {
+    return highLowLabels[label]
+  }
+  const labels = {
+    high: 'High',
+    low: 'Low'
+  };
+  return labels[label]
+};
+
+const predictionFactory = ({ timeline, constituents, start }) => {
+  const getLevel = (hour, modelBaseSpeed, modelU, modelF, modelBaseValue) => {
+    const amplitudes = [];
+    let result = 0;
+
+    constituents.forEach((constituent) => {
+      const amplitude = constituent.amplitude;
+      const phase = constituent._phase;
+      const f = modelF[constituent.name];
+      const speed = modelBaseSpeed[constituent.name];
+      const u = modelU[constituent.name];
+      const V0 = modelBaseValue[constituent.name];
+      amplitudes.push(amplitude * f * Math.cos(speed * hour + (V0 + u) - phase));
+    });
+    // sum up each row
+    amplitudes.forEach((item) => {
+      result += item;
+    });
+    return result
+  };
+
+  const prediction = {};
+
+  prediction.getExtremesPrediction = (options) => {
+    const { labels, offsets } = typeof options !== 'undefined' ? options : {};
+    const results = [];
+    const { baseSpeed, u, f, baseValue } = prepare();
+    let goingUp = false;
+    let goingDown = false;
+    let lastLevel = getLevel(0, baseSpeed, u[0], f[0], baseValue);
+    timeline.items.forEach((time, index) => {
+      const hour = timeline.hours[index];
+      const level = getLevel(hour, baseSpeed, u[index], f[index], baseValue);
+      // Compare this level to the last one, if we
+      // are changing angle, then the last one was high or low
+      if (level > lastLevel && goingDown) {
+        results.push(
+          addExtremesOffsets(
+            {
+              time: timeline.items[index - 1],
+              level: lastLevel,
+              high: false,
+              low: true,
+              label: getExtremeLabel('low', labels)
+            },
+            offsets
+          )
+        );
+      }
+      if (level < lastLevel && goingUp) {
+        results.push(
+          addExtremesOffsets(
+            {
+              time: timeline.items[index - 1],
+              level: lastLevel,
+              high: true,
+              low: false,
+              label: getExtremeLabel('high', labels)
+            },
+            offsets
+          )
+        );
+      }
+      if (level > lastLevel) {
+        goingUp = true;
+        goingDown = false;
+      }
+      if (level < lastLevel) {
+        goingUp = false;
+        goingDown = true;
+      }
+      lastLevel = level;
+    });
+    return results
+  };
+
+  prediction.getTimelinePrediction = () => {
+    const results = [];
+    const { baseSpeed, u, f, baseValue } = prepare();
+    timeline.items.forEach((time, index) => {
+      const hour = timeline.hours[index];
+      const prediction = {
+        time,
+        hour,
+        level: getLevel(hour, baseSpeed, u[index], f[index], baseValue)
+      };
+
+      results.push(prediction);
+    });
+    return results
+  };
+
+  const prepare = () => {
+    const baseAstro = astro(start);
+
+    const baseValue = {};
+    const baseSpeed = {};
+    const u = [];
+    const f = [];
+    constituents.forEach((constituent) => {
+      const value = constituent._model.value(baseAstro);
+      const speed = constituent._model.speed(baseAstro);
+      baseValue[constituent.name] = d2r * value;
+      baseSpeed[constituent.name] = d2r * speed;
+    });
+    timeline.items.forEach((time) => {
+      const uItem = {};
+      const fItem = {};
+      const itemAstro = astro(time);
+      constituents.forEach((constituent) => {
+        const constituentU = modulus(constituent._model.u(itemAstro), 360);
+
+        uItem[constituent.name] = d2r * constituentU;
+        fItem[constituent.name] = modulus(constituent._model.f(itemAstro), 360);
+      });
+      u.push(uItem);
+      f.push(fItem);
+    });
+
+    return {
+      baseValue,
+      baseSpeed,
+      u,
+      f
+    }
+  };
+
+  return Object.freeze(prediction)
+};
+
+const corrections = {
+  fUnity() {
+    return 1
+  },
+
+  // Schureman equations 73, 65
+  fMm(a) {
+    const omega = d2r * a.omega.value;
+    const i = d2r * a.i.value;
+    const I = d2r * a.I.value;
+    const mean =
+      (2 / 3.0 - Math.pow(Math.sin(omega), 2)) *
+      (1 - (3 / 2.0) * Math.pow(Math.sin(i), 2));
+    return (2 / 3.0 - Math.pow(Math.sin(I), 2)) / mean
+  },
+
+  // Schureman equations 74, 66
+  fMf(a) {
+    const omega = d2r * a.omega.value;
+    const i = d2r * a.i.value;
+    const I = d2r * a.I.value;
+    const mean = Math.pow(Math.sin(omega), 2) * Math.pow(Math.cos(0.5 * i), 4);
+    return Math.pow(Math.sin(I), 2) / mean
+  },
+
+  // Schureman equations 75, 67
+  fO1(a) {
+    const omega = d2r * a.omega.value;
+    const i = d2r * a.i.value;
+    const I = d2r * a.I.value;
+    const mean =
+      Math.sin(omega) *
+      Math.pow(Math.cos(0.5 * omega), 2) *
+      Math.pow(Math.cos(0.5 * i), 4);
+    return (Math.sin(I) * Math.pow(Math.cos(0.5 * I), 2)) / mean
+  },
+
+  // Schureman equations 76, 68
+  fJ1(a) {
+    const omega = d2r * a.omega.value;
+    const i = d2r * a.i.value;
+    const I = d2r * a.I.value;
+    const mean =
+      Math.sin(2 * omega) * (1 - (3 / 2.0) * Math.pow(Math.sin(i), 2));
+    return Math.sin(2 * I) / mean
+  },
+
+  // Schureman equations 77, 69
+  fOO1(a) {
+    const omega = d2r * a.omega.value;
+    const i = d2r * a.i.value;
+    const I = d2r * a.I.value;
+    const mean =
+      Math.sin(omega) *
+      Math.pow(Math.sin(0.5 * omega), 2) *
+      Math.pow(Math.cos(0.5 * i), 4);
+    return (Math.sin(I) * Math.pow(Math.sin(0.5 * I), 2)) / mean
+  },
+
+  // Schureman equations 78, 70
+  fM2(a) {
+    const omega = d2r * a.omega.value;
+    const i = d2r * a.i.value;
+    const I = d2r * a.I.value;
+    const mean =
+      Math.pow(Math.cos(0.5 * omega), 4) * Math.pow(Math.cos(0.5 * i), 4);
+    return Math.pow(Math.cos(0.5 * I), 4) / mean
+  },
+
+  // Schureman equations 227, 226, 68
+  // Should probably eventually include the derivations of the magic numbers (0.5023 etc).
+  fK1(a) {
+    const omega = d2r * a.omega.value;
+    const i = d2r * a.i.value;
+    const I = d2r * a.I.value;
+    const nu = d2r * a.nu.value;
+    const sin2IcosnuMean =
+      Math.sin(2 * omega) * (1 - (3 / 2.0) * Math.pow(Math.sin(i), 2));
+    const mean = 0.5023 * sin2IcosnuMean + 0.1681;
+    return (
+      Math.pow(
+        0.2523 * Math.pow(Math.sin(2 * I), 2) +
+          0.1689 * Math.sin(2 * I) * Math.cos(nu) +
+          0.0283,
+        0.5
+      ) / mean
+    )
+  },
+
+  // Schureman equations 215, 213, 204
+  // It can be (and has been) confirmed that the exponent for R_a reads 1/2 via Schureman Table 7
+  fL2(a) {
+    const P = d2r * a.P.value;
+    const I = d2r * a.I.value;
+    const rAInv = Math.pow(
+      1 -
+        12 * Math.pow(Math.tan(0.5 * I), 2) * Math.cos(2 * P) +
+        36 * Math.pow(Math.tan(0.5 * I), 4),
+      0.5
+    );
+    return corrections.fM2(a) * rAInv
+  },
+
+  // Schureman equations 235, 234, 71
+  // Again, magic numbers
+  fK2(a) {
+    const omega = d2r * a.omega.value;
+    const i = d2r * a.i.value;
+    const I = d2r * a.I.value;
+    const nu = d2r * a.nu.value;
+    const sinsqIcos2nuMean =
+      Math.sin(omega) ** 2 * (1 - (3 / 2.0) * Math.sin(i) ** 2);
+    const mean = 0.5023 * sinsqIcos2nuMean + 0.0365;
+    return (
+      Math.pow(
+        0.2523 * Math.pow(Math.sin(I), 4) +
+          0.0367 * Math.pow(Math.sin(I), 2) * Math.cos(2 * nu) +
+          0.0013,
+        0.5
+      ) / mean
+    )
+  },
+  // Schureman equations 206, 207, 195
+  fM1(a) {
+    const P = d2r * a.P.value;
+    const I = d2r * a.I.value;
+    const qAInv = Math.pow(
+      0.25 +
+        1.5 *
+          Math.cos(I) *
+          Math.cos(2 * P) *
+          Math.pow(Math.cos(0.5 * I), -0.5) +
+        2.25 * Math.pow(Math.cos(I), 2) * Math.pow(Math.cos(0.5 * I), -4),
+      0.5
+    );
+    return corrections.fO1(a) * qAInv
+  },
+
+  // See e.g. Schureman equation 149
+  fModd(a, n) {
+    return Math.pow(corrections.fM2(a), n / 2.0)
+  },
+
+  // Node factors u, see Table 2 of Schureman.
+
+  uZero() {
+    return 0.0
+  },
+
+  uMf(a) {
+    return -2.0 * a.xi.value
+  },
+
+  uO1(a) {
+    return 2.0 * a.xi.value - a.nu.value
+  },
+
+  uJ1(a) {
+    return -a.nu.value
+  },
+
+  uOO1(a) {
+    return -2.0 * a.xi.value - a.nu.value
+  },
+
+  uM2(a) {
+    return 2.0 * a.xi.value - 2.0 * a.nu.value
+  },
+
+  uK1(a) {
+    return -a.nup.value
+  },
+
+  // Schureman 214
+  uL2(a) {
+    const I = d2r * a.I.value;
+    const P = d2r * a.P.value;
+    const R =
+      r2d *
+      Math.atan(
+        Math.sin(2 * P) /
+          ((1 / 6.0) * Math.pow(Math.tan(0.5 * I), -2) - Math.cos(2 * P))
+      );
+    return 2.0 * a.xi.value - 2.0 * a.nu.value - R
+  },
+
+  uK2(a) {
+    return -2.0 * a.nupp.value
+  },
+
+  // Schureman 202
+  uM1(a) {
+    const I = d2r * a.I.value;
+    const P = d2r * a.P.value;
+    const Q =
+      r2d *
+      Math.atan(((5 * Math.cos(I) - 1) / (7 * Math.cos(I) + 1)) * Math.tan(P));
+    return a.xi.value - a.nu.value + Q
+  },
+
+  uModd(a, n) {
+    return (n / 2.0) * corrections.uM2(a)
+  }
+};
+
+/**
+ * Computes the dot notation of two arrays
+ * @param {*} a
+ * @param {*} b
+ */
+const dotArray = (a, b) => {
+  const results = [];
+  a.forEach((value, index) => {
+    results.push(value * b[index]);
+  });
+  return results.reduce((total, value) => {
+    return total + value
+  })
+};
+
+const astronimicDoodsonNumber = (astro) => {
+  return [
+    astro['T+h-s'],
+    astro.s,
+    astro.h,
+    astro.p,
+    astro.N,
+    astro.pp,
+    astro['90']
+  ]
+};
+
+const astronomicSpeed = (astro) => {
+  const results = [];
+  astronimicDoodsonNumber(astro).forEach((number) => {
+    results.push(number.speed);
+  });
+  return results
+};
+
+const astronomicValues = (astro) => {
+  const results = [];
+  astronimicDoodsonNumber(astro).forEach((number) => {
+    results.push(number.value);
+  });
+  return results
+};
+
+const constituentFactory = (name, coefficients, u, f) => {
+  if (!coefficients) {
+    throw new Error('Coefficient must be defined for a constituent')
+  }
+
+  const constituent = {
+    name,
+    coefficients,
+
+    value: (astro) => {
+      return dotArray(coefficients, astronomicValues(astro))
+    },
+
+    speed(astro) {
+      return dotArray(coefficients, astronomicSpeed(astro))
+    },
+
+    u: typeof u !== 'undefined' ? u : corrections.uZero,
+
+    f: typeof f !== 'undefined' ? f : corrections.fUnity
+  };
+
+  return Object.freeze(constituent)
+};
+
+const compoundConstituentFactory = (name, members) => {
+  const coefficients = [];
+  members.forEach(({ constituent, factor }) => {
+    constituent.coefficients.forEach((coefficient, index) => {
+      if (typeof coefficients[index] === 'undefined') {
+        coefficients[index] = 0;
+      }
+      coefficients[index] += coefficient * factor;
+    });
+  });
+
+  const compoundConstituent = {
+    name,
+    coefficients,
+
+    speed: (astro) => {
+      let speed = 0;
+      members.forEach(({ constituent, factor }) => {
+        speed += constituent.speed(astro) * factor;
+      });
+      return speed
+    },
+
+    value: (astro) => {
+      let value = 0;
+      members.forEach(({ constituent, factor }) => {
+        value += constituent.value(astro) * factor;
+      });
+      return value
+    },
+
+    u: (astro) => {
+      let u = 0;
+      members.forEach(({ constituent, factor }) => {
+        u += constituent.u(astro) * factor;
+      });
+      return u
+    },
+
+    f: (astro) => {
+      const f = [];
+      members.forEach(({ constituent, factor }) => {
+        f.push(Math.pow(constituent.f(astro), Math.abs(factor)));
+      });
+      return f.reduce((previous, value) => {
+        return previous * value
+      })
+    }
+  };
+
+  return Object.freeze(compoundConstituent)
+};
+
+const constituents = {};
+// Long Term
+constituents.Z0 = constituentFactory('Z0', [0, 0, 0, 0, 0, 0, 0], corrections.uZero, corrections.fUnity);
+constituents.SA = constituentFactory('Sa', [0, 0, 1, 0, 0, 0, 0], corrections.uZero, corrections.fUnity);
+constituents.SSA = constituentFactory(
+  'Ssa',
+  [0, 0, 2, 0, 0, 0, 0],
+  corrections.uZero,
+  corrections.fUnity
+);
+constituents.MM = constituentFactory('MM', [0, 1, 0, -1, 0, 0, 0], corrections.uZero, corrections.fMm);
+constituents.MF = constituentFactory('MF', [0, 2, 0, 0, 0, 0, 0], corrections.uMf, corrections.fMf);
+// Diurnals
+constituents.Q1 = constituentFactory('Q1', [1, -2, 0, 1, 0, 0, 1], corrections.uO1, corrections.fO1);
+constituents.O1 = constituentFactory('O1', [1, -1, 0, 0, 0, 0, 1], corrections.uO1, corrections.fO1);
+constituents.K1 = constituentFactory('K1', [1, 1, 0, 0, 0, 0, -1], corrections.uK1, corrections.fK1);
+constituents.J1 = constituentFactory('J1', [1, 2, 0, -1, 0, 0, -1], corrections.uJ1, corrections.fJ1);
+constituents.M1 = constituentFactory('M1', [1, 0, 0, 0, 0, 0, 1], corrections.uM1, corrections.fM1);
+constituents.P1 = constituentFactory('P1', [1, 1, -2, 0, 0, 0, 1], corrections.uZero, corrections.fUnity);
+constituents.S1 = constituentFactory('S1', [1, 1, -1, 0, 0, 0, 0], corrections.uZero, corrections.fUnity);
+constituents.OO1 = constituentFactory('OO1', [1, 3, 0, 0, 0, 0, -1], corrections.uOO1, corrections.fOO1);
+// Semi diurnals
+constituents['2N2'] = constituentFactory('2N2', [2, -2, 0, 2, 0, 0, 0], corrections.uM2, corrections.fM2);
+constituents.N2 = constituentFactory('N2', [2, -1, 0, 1, 0, 0, 0], corrections.uM2, corrections.fM2);
+constituents.NU2 = constituentFactory('NU2', [2, -1, 2, -1, 0, 0, 0], corrections.uM2, corrections.fM2);
+constituents.M2 = constituentFactory('M2', [2, 0, 0, 0, 0, 0, 0], corrections.uM2, corrections.fM2);
+constituents.LAM2 = constituentFactory('LAM2', [2, 1, -2, 1, 0, 0, 2], corrections.uM2, corrections.fM2);
+constituents.L2 = constituentFactory('L2', [2, 1, 0, -1, 0, 0, 2], corrections.uL2, corrections.fL2);
+constituents.T2 = constituentFactory('T2', [2, 2, -3, 0, 0, 1, 0], corrections.uZero, corrections.fUnity);
+constituents.S2 = constituentFactory('S2', [2, 2, -2, 0, 0, 0, 0], corrections.uZero, corrections.fUnity);
+constituents.R2 = constituentFactory(
+  'R2',
+  [2, 2, -1, 0, 0, -1, 2],
+  corrections.uZero,
+  corrections.fUnity
+);
+constituents.K2 = constituentFactory('K2', [2, 2, 0, 0, 0, 0, 0], corrections.uK2, corrections.fK2);
+// Third diurnal
+constituents.M3 = constituentFactory(
+  'M3',
+  [3, 0, 0, 0, 0, 0, 0],
+  (a) => {
+    return corrections.uModd(a, 3)
+  },
+  (a) => {
+    return corrections.fModd(a, 3)
+  }
+);
+// Compound
+constituents.MSF = compoundConstituentFactory('MSF', [
+  { constituent: constituents.S2, factor: 1 },
+  { constituent: constituents.M2, factor: -1 }
+]);
+
+// Diurnal
+constituents['2Q1'] = compoundConstituentFactory('2Q1', [
+  { constituent: constituents.N2, factor: 1 },
+  { constituent: constituents.J1, factor: -1 }
+]);
+constituents.RHO = compoundConstituentFactory('RHO', [
+  { constituent: constituents.NU2, factor: 1 },
+  { constituent: constituents.K1, factor: -1 }
+]);
+
+// Semi-Diurnal
+
+constituents.MU2 = compoundConstituentFactory('MU2', [
+  { constituent: constituents.M2, factor: 2 },
+  { constituent: constituents.S2, factor: -1 }
+]);
+constituents['2SM2'] = compoundConstituentFactory('2SM2', [
+  { constituent: constituents.S2, factor: 2 },
+  { constituent: constituents.M2, factor: -1 }
+]);
+
+// Third-Diurnal
+constituents['2MK3'] = compoundConstituentFactory('2MK3', [
+  { constituent: constituents.M2, factor: 1 },
+  { constituent: constituents.O1, factor: 1 }
+]);
+constituents.MK3 = compoundConstituentFactory('MK3', [
+  { constituent: constituents.M2, factor: 1 },
+  { constituent: constituents.K1, factor: 1 }
+]);
+
+// Quarter-Diurnal
+constituents.MN4 = compoundConstituentFactory('MN4', [
+  { constituent: constituents.M2, factor: 1 },
+  { constituent: constituents.N2, factor: 1 }
+]);
+constituents.M4 = compoundConstituentFactory('M4', [
+  { constituent: constituents.M2, factor: 2 }
+]);
+constituents.MS4 = compoundConstituentFactory('MS4', [
+  { constituent: constituents.M2, factor: 1 },
+  { constituent: constituents.S2, factor: 1 }
+]);
+constituents.S4 = compoundConstituentFactory('S4', [
+  { constituent: constituents.S2, factor: 2 }
+]);
+
+// Sixth-Diurnal
+constituents.M6 = compoundConstituentFactory('M6', [
+  { constituent: constituents.M2, factor: 3 }
+]);
+constituents.S6 = compoundConstituentFactory('S6', [
+  { constituent: constituents.S2, factor: 3 }
+]);
+
+// Eighth-Diurnals
+constituents.M8 = compoundConstituentFactory('M8', [
+  { constituent: constituents.M2, factor: 4 }
+]);
+
+const getDate = (time) => {
+  if (time instanceof Date) {
+    return time
+  }
+  if (typeof time === 'number') {
+    return new Date(time * 1000)
+  }
+  throw new Error('Invalid date format, should be a Date object, or timestamp')
+};
+
+const getTimeline = (start, end, seconds) => {
+  seconds = typeof seconds !== 'undefined' ? seconds : 10 * 60;
+  const items = [];
+  const endTime = end.getTime() / 1000;
+  let lastTime = start.getTime() / 1000;
+  const startTime = lastTime;
+  const hours = [];
+  while (lastTime <= endTime) {
+    items.push(new Date(lastTime * 1000));
+    hours.push((lastTime - startTime) / (60 * 60));
+    lastTime += seconds;
+  }
+
+  return {
+    items,
+    hours
+  }
+};
+
+const harmonicsFactory = ({ harmonicConstituents, phaseKey, offset }) => {
+  if (!Array.isArray(harmonicConstituents)) {
+    throw new Error('Harmonic constituents are not an array')
+  }
+  const constituents$1 = [];
+  harmonicConstituents.forEach((constituent) => {
+    if (typeof constituent.name === 'undefined') {
+      throw new Error('Harmonic constituents must have a name property')
+    }
+    if (typeof constituents[constituent.name] !== 'undefined') {
+      constituent._model = constituents[constituent.name];
+      constituent._phase = d2r * constituent[phaseKey];
+      constituents$1.push(constituent);
+    }
+  });
+
+  if (offset !== false) {
+    constituents$1.push({
+      name: 'Z0',
+      _model: constituents.Z0,
+      _phase: 0,
+      amplitude: offset
+    });
+  }
+
+  let start = new Date();
+  let end = new Date();
+
+  const harmonics = {};
+
+  harmonics.setTimeSpan = (startTime, endTime) => {
+    start = getDate(startTime);
+    end = getDate(endTime);
+    if (start.getTime() >= end.getTime()) {
+      throw new Error('Start time must be before end time')
+    }
+    return harmonics
+  };
+
+  harmonics.prediction = (options) => {
+    options =
+      typeof options !== 'undefined' ? options : { timeFidelity: 10 * 60 };
+    return predictionFactory({
+      timeline: getTimeline(start, end, options.timeFidelity),
+      constituents: constituents$1,
+      start
+    })
+  };
+
+  return Object.freeze(harmonics)
+};
+
+const tidePredictionFactory = (constituents, options) => {
+  const harmonicsOptions = {
+    harmonicConstituents: constituents,
+    phaseKey: 'phase_GMT',
+    offset: false
+  };
+
+  if (typeof options !== 'undefined') {
+    Object.keys(harmonicsOptions).forEach((key) => {
+      if (typeof options[key] !== 'undefined') {
+        harmonicsOptions[key] = options[key];
+      }
+    });
+  }
+
+  const tidePrediction = {
+    getTimelinePrediction: ({ start, end }) => {
+      return harmonicsFactory(harmonicsOptions)
+        .setTimeSpan(start, end)
+        .prediction()
+        .getTimelinePrediction()
+    },
+
+    getExtremesPrediction: ({ start, end, labels, offsets, timeFidelity }) => {
+      return harmonicsFactory(harmonicsOptions)
+        .setTimeSpan(start, end)
+        .prediction({ timeFidelity })
+        .getExtremesPrediction(labels, offsets)
+    },
+
+    getWaterLevelAtTime: ({ time }) => {
+      const endDate = new Date(time.getTime() + 10 * 60 * 1000);
+      return harmonicsFactory(harmonicsOptions)
+        .setTimeSpan(time, endDate)
+        .prediction()
+        .getTimelinePrediction()[0]
+    }
+  };
+
+  return tidePrediction
+};
+
+module.exports = tidePredictionFactory;
diff --git a/dist/commonjs/package.json b/dist/commonjs/package.json
new file mode 100644
index 0000000..729ac4d
--- /dev/null
+++ b/dist/commonjs/package.json
@@ -0,0 +1 @@
+{"type":"commonjs"}
diff --git a/dist/tide-predictor.js b/dist/web/tide-predictor.js
similarity index 100%
rename from dist/tide-predictor.js
rename to dist/web/tide-predictor.js
diff --git a/dist/tide-predictor.min.js b/dist/web/tide-predictor.min.js
similarity index 100%
rename from dist/tide-predictor.min.js
rename to dist/web/tide-predictor.min.js
diff --git a/package.json b/package.json
index 3d4fa68..7279b8a 100644
--- a/package.json
+++ b/package.json
@@ -7,8 +7,15 @@
   "author": "Kevin Miller <keveemiller@gmail.com>",
   "license": "MIT",
   "type": "module",
-  "module": "./src/index.js",
-  "browser": "./dist/tide-predictor.js",
+  "module": "index.js",
+  "browser": "./dist/web/tide-predictor.js",
+  "commonjs": "./dist/commonjs/index.js",
+  "exports": {
+    ".": {
+      "import": "./src/index.js",
+      "require": "./dist/commonjs/index.js"
+    }
+  },
   "devDependencies": {
     "c8": "^7.11.3",
     "eslint": "^8.18.0",
@@ -23,7 +30,8 @@
     "coverage": "c8 --reporter=lcov mocha --recursive && codecov",
     "ci": "run-s lint test coverage",
     "build:rollup": "rollup --config rollup.config.js",
-    "build:uglify": "uglifyjs ./dist/tide-predictor.js -o ./dist/tide-predictor.min.js",
-    "build": "run-s build:rollup build:uglify"
+    "build:uglify": "uglifyjs ./dist/web/tide-predictor.js -o ./dist/web/tide-predictor.min.js",
+    "build:commonDist": "echo \"{\\\"type\\\":\\\"commonjs\\\"}\" > ./dist/commonjs/package.json",
+    "build": "run-s build:rollup build:commonDist build:uglify"
   }
 }
diff --git a/rollup.config.js b/rollup.config.js
index 6938ac3..9ed4d63 100644
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -8,7 +8,8 @@ export default {
       name: 'tidePredictor',
       file: pkg.browser,
       format: 'umd'
-    }
+    },
+    { file: pkg.commonjs, format: 'commonjs', exports: 'default' }
   ],
   plugins: [
     resolve({