diff --git a/packages/base-n/LICENSE b/packages/base-n/LICENSE
new file mode 100644
index 0000000000..8dada3edaf
--- /dev/null
+++ b/packages/base-n/LICENSE
@@ -0,0 +1,201 @@
+ Apache License
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+ http://www.apache.org/licenses/
+
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diff --git a/packages/base-n/README.md b/packages/base-n/README.md
new file mode 100644
index 0000000000..ef5fca7ec6
--- /dev/null
+++ b/packages/base-n/README.md
@@ -0,0 +1,90 @@
+
+
+# ![base-n](https://media.thi.ng/umbrella/banners/thing-base-n.svg?4cffdce7)
+
+[![npm version](https://img.shields.io/npm/v/@thi.ng/base-n.svg)](https://www.npmjs.com/package/@thi.ng/base-n)
+![npm downloads](https://img.shields.io/npm/dm/@thi.ng/base-n.svg)
+[![Twitter Follow](https://img.shields.io/twitter/follow/thing_umbrella.svg?style=flat-square&label=twitter)](https://twitter.com/thing_umbrella)
+
+This project is part of the
+[@thi.ng/umbrella](https://github.com/thi-ng/umbrella/) monorepo.
+
+- [About](#about)
+ - [Status](#status)
+- [Installation](#installation)
+- [Dependencies](#dependencies)
+- [API](#api)
+- [Authors](#authors)
+- [License](#license)
+
+## About
+
+Arbitrary base-n encoding/decoding with presets for base32/36/58/62/64/85 and support for bigints.
+
+### Status
+
+**BETA** - possibly breaking changes forthcoming
+
+[Search or submit any issues for this package](https://github.com/thi-ng/umbrella/issues?q=%5Bbase-n%5D+in%3Atitle)
+
+## Installation
+
+```bash
+yarn add @thi.ng/base-n
+```
+
+```html
+// ES module
+
+
+// UMD
+
+```
+
+Package sizes (gzipped, pre-treeshake): ESM: 626 bytes / CJS: 715 bytes / UMD: 800 bytes
+
+## Dependencies
+
+None
+
+## API
+
+[Generated API docs](https://docs.thi.ng/umbrella/base-n/)
+
+```ts
+import { BASE85, defBase } from "@thi.ng/base-n";
+
+BASE85.encodeBigInt(2n ** 128n - 1);
+// '=r54lj&NUUO~Hi%c2ym0'
+
+BASE85.decodeBigInt("=r54lj&NUUO~Hi%c2ym0").toString(16);
+// 'ffffffffffffffffffffffffffffffff'
+
+// define a custom base impl
+const ternary = defBase("012");
+
+ternary.encode(12345678)
+// '212020020002100'
+
+ternary.decode("212020020002100");
+// 12345678
+```
+
+## Authors
+
+Karsten Schmidt
+
+If this project contributes to an academic publication, please cite it as:
+
+```bibtex
+@misc{thing-base-n,
+ title = "@thi.ng/base-n",
+ author = "Karsten Schmidt",
+ note = "https://thi.ng/base-n",
+ year = 2017
+}
+```
+
+## License
+
+© 2017 - 2021 Karsten Schmidt // Apache Software License 2.0
diff --git a/packages/base-n/api-extractor.json b/packages/base-n/api-extractor.json
new file mode 100644
index 0000000000..94972e6bed
--- /dev/null
+++ b/packages/base-n/api-extractor.json
@@ -0,0 +1,3 @@
+{
+ "extends": "../../api-extractor.json"
+}
diff --git a/packages/base-n/package.json b/packages/base-n/package.json
new file mode 100644
index 0000000000..234e825389
--- /dev/null
+++ b/packages/base-n/package.json
@@ -0,0 +1,67 @@
+{
+ "name": "@thi.ng/base-n",
+ "version": "0.0.1",
+ "description": "Arbitrary base-n encoding/decoding with presets for base32/36/58/62/64/85 and support for bigints",
+ "module": "./index.js",
+ "main": "./lib/index.js",
+ "umd:main": "./lib/index.umd.js",
+ "typings": "./index.d.ts",
+ "repository": {
+ "type": "git",
+ "url": "https://github.com/thi-ng/umbrella.git"
+ },
+ "homepage": "https://github.com/thi-ng/umbrella/tree/master/packages/base-n#readme",
+ "funding": [
+ {
+ "type": "github",
+ "url": "https://github.com/sponsors/postspectacular"
+ },
+ {
+ "type": "patreon",
+ "url": "https://patreon.com/thing_umbrella"
+ }
+ ],
+ "author": "Karsten Schmidt ",
+ "license": "Apache-2.0",
+ "scripts": {
+ "build": "yarn clean && yarn build:es6 && node ../../scripts/bundle-module",
+ "build:release": "yarn clean && yarn build:es6 && node ../../scripts/bundle-module all",
+ "build:es6": "tsc --declaration",
+ "build:test": "rimraf build && tsc -p test/tsconfig.json",
+ "build:check": "tsc --isolatedModules --noEmit",
+ "test": "mocha test",
+ "cover": "nyc mocha test && nyc report --reporter=lcov",
+ "clean": "rimraf *.js *.d.ts *.map .nyc_output build coverage doc lib",
+ "doc:readme": "ts-node -P ../../tools/tsconfig.json ../../tools/src/readme.ts",
+ "doc:ae": "mkdir -p .ae/doc .ae/temp && node_modules/.bin/api-extractor run --local --verbose",
+ "doc": "node_modules/.bin/typedoc --out doc --theme ../../tools/doc/typedoc-theme src/index.ts",
+ "pub": "yarn build:release && yarn publish --access public"
+ },
+ "devDependencies": {
+ "@istanbuljs/nyc-config-typescript": "^1.0.1",
+ "@microsoft/api-extractor": "^7.12.1",
+ "@types/mocha": "^8.2.0",
+ "@types/node": "^14.14.14",
+ "mocha": "^8.2.1",
+ "nyc": "^15.1.0",
+ "ts-node": "^9.1.1",
+ "typedoc": "^0.20.4",
+ "typescript": "^4.1.3"
+ },
+ "files": [
+ "*.js",
+ "*.d.ts",
+ "lib"
+ ],
+ "keywords": [
+ "typescript"
+ ],
+ "publishConfig": {
+ "access": "public"
+ },
+ "sideEffects": false,
+ "thi.ng": {
+ "status": "beta",
+ "year": 2017
+ }
+}
diff --git a/packages/base-n/src/32.ts b/packages/base-n/src/32.ts
new file mode 100644
index 0000000000..0a2e131451
--- /dev/null
+++ b/packages/base-n/src/32.ts
@@ -0,0 +1,17 @@
+import { defBase } from "./base";
+
+/**
+ * Digits: A-Z 2-7
+ *
+ * @remarks
+ * Reference: https://tools.ietf.org/html/rfc4648
+ */
+export const BASE32_RFC4648 = defBase("ABCDEFGHIJKLMNOPQRSTUVWXYZ234567");
+
+/**
+ * Digits: 0-9 A-V
+ *
+ * @remarks
+ * Reference: https://en.wikipedia.org/wiki/Base32#base32hex
+ */
+export const BASE32_HEX = defBase("0123456789ABCDEFGHIJKLMNOPQRSTUV");
diff --git a/packages/base-n/src/36.ts b/packages/base-n/src/36.ts
new file mode 100644
index 0000000000..99f02821ae
--- /dev/null
+++ b/packages/base-n/src/36.ts
@@ -0,0 +1,11 @@
+import { defBase } from "./base";
+
+export const B36_CHARS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+/**
+ * Digits: 0-9 A-Z
+ *
+ * @remarks
+ * Reference: https://en.wikipedia.org/wiki/Base36
+ */
+export const BASE36 = defBase(B36_CHARS);
diff --git a/packages/base-n/src/58.ts b/packages/base-n/src/58.ts
new file mode 100644
index 0000000000..70ae485c16
--- /dev/null
+++ b/packages/base-n/src/58.ts
@@ -0,0 +1,9 @@
+import { defBase } from "./base";
+
+export const B58_CHARS =
+ "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
+
+/**
+ * Reference: https://en.wikipedia.org/wiki/Binary-to-text_encoding
+ */
+export const BASE58 = defBase(B58_CHARS);
diff --git a/packages/base-n/src/62.ts b/packages/base-n/src/62.ts
new file mode 100644
index 0000000000..e88f53535f
--- /dev/null
+++ b/packages/base-n/src/62.ts
@@ -0,0 +1,12 @@
+import { B36_CHARS } from "./36";
+import { defBase } from "./base";
+
+export const B62_CHARS = B36_CHARS + "abcdefghijklmnopqrstuvwxyz";
+
+/**
+ * Digits: 0-9 A-Z a-z
+ *
+ * @remarks
+ * Reference: https://en.wikipedia.org/wiki/Base62
+ */
+export const BASE62 = defBase(B62_CHARS);
diff --git a/packages/base-n/src/64.ts b/packages/base-n/src/64.ts
new file mode 100644
index 0000000000..4a55b453a2
--- /dev/null
+++ b/packages/base-n/src/64.ts
@@ -0,0 +1,12 @@
+import { B62_CHARS } from "./62";
+import { defBase } from "./base";
+
+export const B64_CHARS = B62_CHARS + "+/";
+
+/**
+ * Digits: 0-9 A-Z a-z + /
+ *
+ * @remarks
+ * Reference: https://en.wikipedia.org/wiki/Base64
+ */
+export const BASE64 = defBase(B64_CHARS);
diff --git a/packages/base-n/src/85.ts b/packages/base-n/src/85.ts
new file mode 100644
index 0000000000..64f0ab28b2
--- /dev/null
+++ b/packages/base-n/src/85.ts
@@ -0,0 +1,9 @@
+import { B62_CHARS } from "./62";
+import { defBase } from "./base";
+
+const B85_CHARS = B62_CHARS + "!#$%&()*+-;<=>?@^_`{|}~";
+
+/**
+ * Reference: https://en.wikipedia.org/wiki/Ascii85
+ */
+export const BASE85 = defBase(B85_CHARS);
diff --git a/packages/base-n/src/api.ts b/packages/base-n/src/api.ts
new file mode 100644
index 0000000000..ca1f6f51a5
--- /dev/null
+++ b/packages/base-n/src/api.ts
@@ -0,0 +1,28 @@
+export interface IBase {
+ /**
+ * Encodes `x` into a baseN encoded string. `x` MUST be < 2^53. Use
+ * `encodeBigInt()` for arbitrary values.
+ *
+ * @param x
+ */
+ encode(x: number): string;
+ /**
+ * Encodes bigint `x` into a baseN encoded string.
+ *
+ * @param x
+ */
+ encodeBigInt(x: bigint): string;
+ /**
+ * Decodes baseN encoded string `x` into a numeric value. Assumes the
+ * resulting `x` will be < 2^53. Use `decodeBigInt()` for arbitrary values.
+ *
+ * @param x
+ */
+ decode(x: string): number;
+ /**
+ * Decodes baseN encoded string `x` into a bigint value.
+ *
+ * @param x
+ */
+ decodeBigInt(x: string): bigint;
+}
diff --git a/packages/base-n/src/base.ts b/packages/base-n/src/base.ts
new file mode 100644
index 0000000000..a60720b371
--- /dev/null
+++ b/packages/base-n/src/base.ts
@@ -0,0 +1,63 @@
+import type { IBase } from "./api";
+
+export const defBase = (chars: string) => new BaseN(chars);
+
+export class BaseN implements IBase {
+ readonly N: number;
+ readonly index: Record;
+
+ constructor(public readonly base: string) {
+ this.N = base.length;
+ this.index = [...base].reduce(
+ (acc, x, i) => ((acc[x] = i), acc),
+ >{}
+ );
+ }
+
+ encode(x: number) {
+ const { base, N } = this;
+ if (x === 0) return base[0];
+ let res = "";
+ while (x > 0) {
+ res = base[x % N] + res;
+ x = (x / N) | 0;
+ }
+ return res;
+ }
+
+ encodeBigInt(x: bigint) {
+ if (x < BigInt(2 ** 53)) return this.encode(Number(x));
+ const { base, N } = this;
+ if (x === BigInt(0)) return base[0];
+ const NN = BigInt(N);
+ let res = "";
+ while (x > 0) {
+ res = base[Number(x % NN)] + res;
+ x /= NN;
+ }
+ return res;
+ }
+
+ decode(x: string) {
+ const { index, N } = this;
+ let res = 0;
+ for (let n = x.length - 1, i = 0; i <= n; i++) {
+ res += index[x[i]] * N ** (n - i);
+ }
+ return res;
+ }
+
+ decodeBigInt(x: string): bigint {
+ const { index, N } = this;
+ const NN = BigInt(N);
+ let res = BigInt(0);
+ for (let n = x.length - 1, i = 0; i <= n; i++) {
+ res += BigInt(index[x[i]]) * NN ** BigInt(n - i);
+ }
+ return res;
+ }
+
+ validate(x: string) {
+ return new RegExp(`^[${this.base}]+$`).test(x);
+ }
+}
diff --git a/packages/base-n/src/index.ts b/packages/base-n/src/index.ts
new file mode 100644
index 0000000000..15bde395a5
--- /dev/null
+++ b/packages/base-n/src/index.ts
@@ -0,0 +1,9 @@
+export * from "./api";
+export * from "./base";
+
+export * from "./32";
+export * from "./36";
+export * from "./58";
+export * from "./62";
+export * from "./64";
+export * from "./85";
diff --git a/packages/base-n/test/index.ts b/packages/base-n/test/index.ts
new file mode 100644
index 0000000000..2a0d89cd04
--- /dev/null
+++ b/packages/base-n/test/index.ts
@@ -0,0 +1,37 @@
+import * as assert from "assert";
+import {
+ BASE32_HEX,
+ BASE32_RFC4648,
+ BASE36,
+ BASE58,
+ BASE64,
+ BASE85,
+} from "../src";
+
+describe("base-n", () => {
+ it("roundtrip", () => {
+ const X = BigInt(2) ** BigInt(128) - BigInt(1);
+
+ // prettier-ignore
+ assert.strictEqual(BASE32_RFC4648.encodeBigInt(X), "H7777777777777777777777777");
+ // prettier-ignore
+ assert.strictEqual(BASE32_RFC4648.decodeBigInt("H7777777777777777777777777"), X);
+
+ // prettier-ignore
+ assert.strictEqual(BASE32_HEX.encodeBigInt(X), "7VVVVVVVVVVVVVVVVVVVVVVVVV");
+ // prettier-ignore
+ assert.strictEqual(BASE32_HEX.decodeBigInt("7VVVVVVVVVVVVVVVVVVVVVVVVV"), X);
+
+ assert.strictEqual(BASE36.encodeBigInt(X), "F5LXX1ZZ5PNORYNQGLHZMSP33");
+ assert.strictEqual(BASE36.decodeBigInt("F5LXX1ZZ5PNORYNQGLHZMSP33"), X);
+
+ assert.strictEqual(BASE58.encodeBigInt(X), "YcVfxkQb6JRzqk5kF2tNLv");
+ assert.strictEqual(BASE58.decodeBigInt("YcVfxkQb6JRzqk5kF2tNLv"), X);
+
+ assert.strictEqual(BASE64.encodeBigInt(X), "3/////////////////////");
+ assert.strictEqual(BASE64.decodeBigInt("3/////////////////////"), X);
+
+ assert.strictEqual(BASE85.encodeBigInt(X), "=r54lj&NUUO~Hi%c2ym0");
+ assert.strictEqual(BASE85.decodeBigInt("=r54lj&NUUO~Hi%c2ym0"), X);
+ });
+});
diff --git a/packages/base-n/test/tsconfig.json b/packages/base-n/test/tsconfig.json
new file mode 100644
index 0000000000..f6e63560dd
--- /dev/null
+++ b/packages/base-n/test/tsconfig.json
@@ -0,0 +1,11 @@
+{
+ "extends": "../../../tsconfig.json",
+ "compilerOptions": {
+ "outDir": "../build",
+ "module": "commonjs"
+ },
+ "include": [
+ "./**/*.ts",
+ "../src/**/*.ts"
+ ]
+}
diff --git a/packages/base-n/tpl.readme.md b/packages/base-n/tpl.readme.md
new file mode 100644
index 0000000000..4319daa09e
--- /dev/null
+++ b/packages/base-n/tpl.readme.md
@@ -0,0 +1,67 @@
+# ${pkg.banner}
+
+[![npm version](https://img.shields.io/npm/v/${pkg.name}.svg)](https://www.npmjs.com/package/${pkg.name})
+![npm downloads](https://img.shields.io/npm/dm/${pkg.name}.svg)
+[![Twitter Follow](https://img.shields.io/twitter/follow/thing_umbrella.svg?style=flat-square&label=twitter)](https://twitter.com/thing_umbrella)
+
+This project is part of the
+[@thi.ng/umbrella](https://github.com/thi-ng/umbrella/) monorepo.
+
+
+
+## About
+
+${pkg.description}
+
+${status}
+
+${supportPackages}
+
+${relatedPackages}
+
+${blogPosts}
+
+## Installation
+
+${pkg.install}
+
+${pkg.size}
+
+## Dependencies
+
+${pkg.deps}
+
+${examples}
+
+## API
+
+${docLink}
+
+```ts
+import { BASE85, defBase } from "@thi.ng/base-n";
+
+BASE85.encodeBigInt(2n ** 128n - 1);
+// '=r54lj&NUUO~Hi%c2ym0'
+
+BASE85.decodeBigInt("=r54lj&NUUO~Hi%c2ym0").toString(16);
+// 'ffffffffffffffffffffffffffffffff'
+
+// define a custom base impl
+const ternary = defBase("012");
+
+ternary.encode(12345678)
+// '212020020002100'
+
+ternary.decode("212020020002100");
+// 12345678
+```
+
+## Authors
+
+${authors}
+
+${pkg.cite}
+
+## License
+
+© ${copyright} // ${license}
diff --git a/packages/base-n/tsconfig.json b/packages/base-n/tsconfig.json
new file mode 100644
index 0000000000..bd6481a5a6
--- /dev/null
+++ b/packages/base-n/tsconfig.json
@@ -0,0 +1,9 @@
+{
+ "extends": "../../tsconfig.json",
+ "compilerOptions": {
+ "outDir": "."
+ },
+ "include": [
+ "./src/**/*.ts"
+ ]
+}