diff --git a/CHANGELOG.md b/CHANGELOG.md
index 55ea89a..1e25852 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,11 @@
 
 ## v3.0.0 - unreleased
 
+Most notably, v3 switches the letter case of generated IDs from uppercase (e.g.,
+"036Z951MHJIKZIK2GSL81GR7L") to lowercase (e.g., "036z951mhjikzik2gsl81gr7l"),
+though it is technically not supposed to break existing code because SCRU128 is
+a case-insensitive scheme. Other changes include the removal of deprecated APIs.
+
 ### Removed
 
 - CommonJS entry point
@@ -14,6 +19,10 @@
   in Node v14 or older where Web Crypto API is not yet available
 - Non-ESM browser test runner
 
+### Changed
+
+- Letter case of generated IDs from uppercase to lowercase
+
 ## v2.5.0 - 2023-06-21
 
 ### Added
diff --git a/README.md b/README.md
index 72ebe84..bd14a6d 100644
--- a/README.md
+++ b/README.md
@@ -17,15 +17,15 @@ decentralized, globally unique time-ordered identifiers. SCRU128 is inspired by
 ```javascript
 import { scru128, scru128String } from "scru128";
 // or on browsers:
-// import { scru128, scru128String } from "https://unpkg.com/scru128@^2";
+// import { scru128, scru128String } from "https://unpkg.com/scru128@^3";
 
 // generate a new identifier object
 const x = scru128();
-console.log(String(x)); // e.g. "036Z951MHJIKZIK2GSL81GR7L"
+console.log(String(x)); // e.g., "036z951mhjikzik2gsl81gr7l"
 console.log(x.toBigInt()); // as a 128-bit unsigned integer
 
 // generate a textual representation directly
-console.log(scru128String()); // e.g. "036Z951MHZX67T63MQ9XE6Q0J"
+console.log(scru128String()); // e.g., "036z951mhzx67t63mq9xe6q0j"
 ```
 
 See [SCRU128 Specification] for details.
diff --git a/src/index.ts b/src/index.ts
index 427ea9b..d2bf3d2 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -5,15 +5,15 @@
  * ```javascript
  * import { scru128, scru128String } from "scru128";
  * // or on browsers:
- * // import { scru128, scru128String } from "https://unpkg.com/scru128@^2";
+ * // import { scru128, scru128String } from "https://unpkg.com/scru128@^3";
  *
  * // generate a new identifier object
  * const x = scru128();
- * console.log(String(x)); // e.g. "036Z951MHJIKZIK2GSL81GR7L"
+ * console.log(String(x)); // e.g., "036z951mhjikzik2gsl81gr7l"
  * console.log(x.toBigInt()); // as a 128-bit unsigned integer
  *
  * // generate a textual representation directly
- * console.log(scru128String()); // e.g. "036Z951MHZX67T63MQ9XE6Q0J"
+ * console.log(scru128String()); // e.g., "036z951mhzx67t63mq9xe6q0j"
  * ```
  *
  * @packageDocumentation
@@ -29,7 +29,7 @@ const MAX_COUNTER_HI = 0xff_ffff;
 const MAX_COUNTER_LO = 0xff_ffff;
 
 /** Digit characters used in the Base36 notation. */
-const DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+const DIGITS = "0123456789abcdefghijklmnopqrstuvwxyz";
 
 /** An O(1) map from ASCII code points to Base36 digit values. */
 const DECODE_MAP = [
@@ -55,7 +55,7 @@ const DEFAULT_ROLLBACK_ALLOWANCE = 10_000; // 10 seconds
  * ```javascript
  * import { Scru128Id } from "scru128";
  *
- * const x = Scru128Id.fromString("036Z968FU2TUGY7SVKFZNEWKK");
+ * const x = Scru128Id.fromString("036z968fu2tugy7svkfznewkk");
  * console.log(String(x));
  *
  * const y = Scru128Id.fromBigInt(0x017fa1de51a80fd992f9e8cc2d5eb88en);
@@ -592,9 +592,9 @@ export class Scru128Generator {
    * import { Scru128Generator } from "scru128";
    *
    * const [a, b, c] = new Scru128Generator();
-   * console.log(String(a)); // e.g. "038MQR9E14CJC12DH9AMW7I5O"
-   * console.log(String(b)); // e.g. "038MQR9E14CJC12DH9DTPWFR3"
-   * console.log(String(c)); // e.g. "038MQR9E14CJC12DH9E6RJMQI"
+   * console.log(String(a)); // e.g., "038mqr9e14cjc12dh9amw7i5o"
+   * console.log(String(b)); // e.g., "038mqr9e14cjc12dh9dtpwfr3"
+   * console.log(String(c)); // e.g., "038mqr9e14cjc12dh9e6rjmqi"
    * ```
    */
   [Symbol.iterator](): Iterator<Scru128Id, undefined> {
diff --git a/test/identifier.mjs b/test/identifier.mjs
index 48a2007..e313e0c 100644
--- a/test/identifier.mjs
+++ b/test/identifier.mjs
@@ -40,8 +40,8 @@ describe("Scru128Id", function () {
       const fromString = Scru128Id.fromString(e[1]);
 
       assert(fromFields.equals(fromString));
-      assert(fromFields.toString() === e[1].toUpperCase());
-      assert(fromString.toString() === e[1].toUpperCase());
+      assert(fromFields.toString() === e[1].toLowerCase());
+      assert(fromString.toString() === e[1].toLowerCase());
       for (let i = 0; i < fs.length; i++) {
         assert(fromFields[fs[i]] === e[0][i]);
         assert(fromString[fs[i]] === e[0][i]);
@@ -52,25 +52,25 @@ describe("Scru128Id", function () {
   it("throws error if an invalid string representation is supplied", function () {
     const cases = [
       "",
-      " 036Z8PUQ4TSXSIGK6O19Y164Q",
-      "036Z8PUQ54QNY1VQ3HCBRKWEB ",
-      " 036Z8PUQ54QNY1VQ3HELIVWAX ",
-      "+036Z8PUQ54QNY1VQ3HFCV3SS0",
-      "-036Z8PUQ54QNY1VQ3HHY8U1CH",
-      "+36Z8PUQ54QNY1VQ3HJQ48D9P",
-      "-36Z8PUQ5A7J0TI08OZ6ZDRDY",
-      "036Z8PUQ5A7J0T_08P2CDZ28V",
-      "036Z8PU-5A7J0TI08P3OL8OOL",
-      "036Z8PUQ5A7J0TI08P4J 6CYA",
-      "F5LXX1ZZ5PNORYNQGLHZMSP34",
-      "ZZZZZZZZZZZZZZZZZZZZZZZZZ",
-      "039O\tVVKLFMQLQE7FZLLZ7C7T",
-      "039ONVVKLFMQLQ漢字FGVD1",
-      "039ONVVKL🤣QE7FZR2HDOQU",
-      "頭ONVVKLFMQLQE7FZRHTGCFZ",
-      "039ONVVKLFMQLQE7FZTFT5尾",
-      "039漢字A52XP4BVF4SN94E09CJA",
-      "039OOA52XP4BV😘SN97642MWL",
+      " 036z8puq4tsxsigk6o19y164q",
+      "036z8puq54qny1vq3hcbrkweb ",
+      " 036z8puq54qny1vq3helivwax ",
+      "+036z8puq54qny1vq3hfcv3ss0",
+      "-036z8puq54qny1vq3hhy8u1ch",
+      "+36z8puq54qny1vq3hjq48d9p",
+      "-36z8puq5a7j0ti08oz6zdrdy",
+      "036z8puq5a7j0t_08p2cdz28v",
+      "036z8pu-5a7j0ti08p3ol8ool",
+      "036z8puq5a7j0ti08p4j 6cya",
+      "f5lxx1zz5pnorynqglhzmsp34",
+      "zzzzzzzzzzzzzzzzzzzzzzzzz",
+      "039o\tvvklfmqlqe7fzllz7c7t",
+      "039onvvklfmqlq漢字fgvd1",
+      "039onvvkl🤣qe7fzr2hdoqu",
+      "頭onvvklfmqlqe7fzrhtgcfz",
+      "039onvvklfmqlqe7fztft5尾",
+      "039漢字a52xp4bvf4sn94e09cja",
+      "039ooa52xp4bv😘sn97642mwl",
     ];
 
     for (const e of cases) {
diff --git a/test/index.mjs b/test/index.mjs
index bc04683..e1713ae 100644
--- a/test/index.mjs
+++ b/test/index.mjs
@@ -27,7 +27,7 @@ describe("scru128String()", function () {
   }
 
   it("generates 25-digit canonical string", function () {
-    const re = /^[0-9A-Z]{25}$/;
+    const re = /^[0-9a-z]{25}$/;
     assert(samples.every((e) => typeof e === "string" && re.test(e)));
   });