diff --git a/src/blst/index.ts b/src/blst/index.ts
index 49d9bbf..83d05a4 100644
--- a/src/blst/index.ts
+++ b/src/blst/index.ts
@@ -4,6 +4,7 @@ import {PrivateKey} from "./privateKey";
 import {PublicKey} from "./publicKey";
 import {Signature} from "./signature";
 import {toBuffer} from "../helpers/utils";
+import {IBls} from "../interface";
 export * from "../constants";
 
 export {Keypair, PrivateKey, PublicKey, Signature};
@@ -15,23 +16,6 @@ export function destroy(): void {
   // Native bindings require no destroy() call
 }
 
-/**
- * Generates new secret and public key
- */
-export function generateKeyPair(): Keypair {
-  return Keypair.generate();
-}
-
-/**
- * Generates public key from given secret.
- * @param {BLSSecretKey} secretKey
- */
-export function generatePublicKey(secretKey: Uint8Array): Buffer {
-  assert(secretKey, "secretKey is null or undefined");
-  const keypair = new Keypair(PrivateKey.fromBytes(toBuffer(secretKey)));
-  return keypair.publicKey.toBytes();
-}
-
 /**
  * Signs given message using secret key.
  * @param secretKey
@@ -127,9 +111,7 @@ export function verifyMultiple(publicKeys: Uint8Array[], messageHashes: Uint8Arr
   }
 }
 
-export default {
-  generateKeyPair,
-  generatePublicKey,
+const bls: IBls = {
   sign,
   aggregateSignatures,
   aggregatePubkeys,
@@ -137,10 +119,12 @@ export default {
   verifyAggregate,
   verifyMultiple,
 
-  Keypair,
+  // Keypair,
   PrivateKey,
   PublicKey,
   Signature,
   initBLS,
   destroy,
 };
+
+export default bls;
diff --git a/src/blst/keypair.ts b/src/blst/keypair.ts
index 2e34c54..db3928e 100644
--- a/src/blst/keypair.ts
+++ b/src/blst/keypair.ts
@@ -1,7 +1,8 @@
 import {PublicKey} from "./publicKey";
 import {PrivateKey} from "./privateKey";
+import {IKeypair} from "../interface";
 
-export class Keypair {
+export class Keypair implements IKeypair {
   private readonly _publicKey: PublicKey;
 
   private readonly _privateKey: PrivateKey;
diff --git a/src/blst/privateKey.ts b/src/blst/privateKey.ts
index c375cf6..a421147 100644
--- a/src/blst/privateKey.ts
+++ b/src/blst/privateKey.ts
@@ -1,9 +1,10 @@
 import * as blst from "@chainsafe/blst";
 import {bytesToHex, getRandomBytes, hexToBytes} from "../helpers/utils";
+import {IPrivateKey} from "../interface";
 import {PublicKey} from "./publicKey";
 import {Signature} from "./signature";
 
-export class PrivateKey {
+export class PrivateKey implements IPrivateKey {
   readonly value: blst.SecretKey;
 
   constructor(value: blst.SecretKey) {
@@ -25,7 +26,7 @@ export class PrivateKey {
   }
 
   signMessage(message: Uint8Array): Signature {
-    return Signature.fromValue(this.value.sign(message));
+    return new Signature(this.value.sign(message));
   }
 
   toPublicKey(): PublicKey {
diff --git a/src/blst/publicKey.ts b/src/blst/publicKey.ts
index 67f5281..ee28c5c 100644
--- a/src/blst/publicKey.ts
+++ b/src/blst/publicKey.ts
@@ -1,8 +1,9 @@
 import * as blst from "@chainsafe/blst";
 import {bytesToHex, hexToBytes} from "../helpers/utils";
+import {IPublicKey} from "../interface";
 import {Signature} from "./signature";
 
-export class PublicKey {
+export class PublicKey implements IPublicKey {
   readonly affine: blst.PublicKey;
   readonly jacobian: blst.AggregatePublicKey;
 
diff --git a/src/blst/signature.ts b/src/blst/signature.ts
index eed4ded..5bad9d1 100644
--- a/src/blst/signature.ts
+++ b/src/blst/signature.ts
@@ -1,8 +1,9 @@
 import * as blst from "@chainsafe/blst";
 import {bytesToHex, hexToBytes} from "../helpers/utils";
+import {ISignature} from "../interface";
 import {PublicKey} from "./publicKey";
 
-export class Signature {
+export class Signature implements ISignature {
   readonly affine: blst.Signature;
 
   constructor(value: blst.Signature) {
@@ -17,10 +18,6 @@ export class Signature {
     return this.fromBytes(hexToBytes(hex));
   }
 
-  static fromValue(signature: blst.Signature): Signature {
-    return new Signature(signature);
-  }
-
   static aggregate(signatures: Signature[]): Signature {
     const agg = blst.AggregateSignature.fromSignatures(signatures.map((sig) => sig.affine));
     return new Signature(agg.toSignature());
diff --git a/src/herumi/context.ts b/src/herumi/context.ts
index 65992a4..65d5248 100644
--- a/src/herumi/context.ts
+++ b/src/herumi/context.ts
@@ -3,18 +3,17 @@ import bls from "@chainsafe/eth2-bls-wasm";
 
 type Bls = typeof bls;
 let blsGlobal: Bls | null = null;
-let blsGlobalPromise: Promise<Bls> | null = null;
+let blsGlobalPromise: Promise<void> | null = null;
 
-export async function setupBls(): Promise<Bls> {
+export async function setupBls(): Promise<void> {
   if (!blsGlobal) {
     await bls.init();
     blsGlobal = bls;
   }
-  return blsGlobal;
 }
 
 // Cache a promise for Bls instead of Bls to make sure it is initialized only once
-export async function initBLS(): Promise<Bls> {
+export async function initBLS(): Promise<void> {
   if (!blsGlobalPromise) {
     blsGlobalPromise = setupBls();
   }
diff --git a/src/herumi/index.ts b/src/herumi/index.ts
index 4ee3138..6c03481 100644
--- a/src/herumi/index.ts
+++ b/src/herumi/index.ts
@@ -5,26 +5,10 @@ import {Signature} from "./signature";
 import {initBLS, destroy} from "./context";
 import assert from "assert";
 import {toBuffer} from "../helpers/utils";
+import {IBls} from "../interface";
 
 export {Keypair, PrivateKey, PublicKey, Signature, initBLS, destroy};
 
-/**
- * Generates new secret and public key
- */
-export function generateKeyPair(): Keypair {
-  return Keypair.generate();
-}
-
-/**
- * Generates public key from given secret.
- * @param {BLSSecretKey} secretKey
- */
-export function generatePublicKey(secretKey: Uint8Array): Buffer {
-  assert(secretKey, "secretKey is null or undefined");
-  const keypair = new Keypair(PrivateKey.fromBytes(toBuffer(secretKey)));
-  return keypair.publicKey.toBytes();
-}
-
 /**
  * Signs given message using secret key.
  * @param secretKey
@@ -121,9 +105,7 @@ export function verifyMultiple(publicKeys: Uint8Array[], messageHashes: Uint8Arr
   }
 }
 
-export default {
-  generateKeyPair,
-  generatePublicKey,
+const bls: IBls = {
   sign,
   aggregateSignatures,
   aggregatePubkeys,
@@ -131,10 +113,12 @@ export default {
   verifyAggregate,
   verifyMultiple,
 
-  Keypair,
+  // Keypair,
   PrivateKey,
   PublicKey,
   Signature,
   initBLS,
   destroy,
 };
+
+export default bls;
diff --git a/src/herumi/keypair.ts b/src/herumi/keypair.ts
index 2e34c54..db3928e 100644
--- a/src/herumi/keypair.ts
+++ b/src/herumi/keypair.ts
@@ -1,7 +1,8 @@
 import {PublicKey} from "./publicKey";
 import {PrivateKey} from "./privateKey";
+import {IKeypair} from "../interface";
 
-export class Keypair {
+export class Keypair implements IKeypair {
   private readonly _publicKey: PublicKey;
 
   private readonly _privateKey: PrivateKey;
diff --git a/src/herumi/privateKey.ts b/src/herumi/privateKey.ts
index c791d2f..facdd59 100644
--- a/src/herumi/privateKey.ts
+++ b/src/herumi/privateKey.ts
@@ -6,8 +6,9 @@ import {getContext} from "./context";
 import {PublicKey} from "./publicKey";
 import {Signature} from "./signature";
 import {bytesToHex, hexToBytes} from "../helpers/utils";
+import {IPrivateKey} from "../interface";
 
-export class PrivateKey {
+export class PrivateKey implements IPrivateKey {
   readonly value: SecretKeyType;
 
   constructor(value: SecretKeyType) {
diff --git a/src/herumi/publicKey.ts b/src/herumi/publicKey.ts
index f104a09..4cd01cc 100644
--- a/src/herumi/publicKey.ts
+++ b/src/herumi/publicKey.ts
@@ -3,8 +3,9 @@ import {getContext} from "./context";
 import {EMPTY_PUBLIC_KEY} from "../constants";
 import {Signature} from "./signature";
 import {bytesToHex, hexToBytes, isEqualBytes} from "../helpers/utils";
+import {IPublicKey} from "../interface";
 
-export class PublicKey {
+export class PublicKey implements IPublicKey {
   readonly value: PublicKeyType;
 
   constructor(value: PublicKeyType) {
diff --git a/src/herumi/signature.ts b/src/herumi/signature.ts
index 4995ba1..3bf8a22 100644
--- a/src/herumi/signature.ts
+++ b/src/herumi/signature.ts
@@ -4,8 +4,9 @@ import {SignatureType} from "@chainsafe/eth2-bls-wasm";
 import {getContext} from "./context";
 import {PublicKey} from "./publicKey";
 import {bytesToHex, hexToBytes, isEqualBytes} from "../helpers/utils";
+import {ISignature} from "../interface";
 
-export class Signature {
+export class Signature implements ISignature {
   readonly value: SignatureType;
 
   constructor(value: SignatureType) {
diff --git a/src/interface.ts b/src/interface.ts
new file mode 100644
index 0000000..756362a
--- /dev/null
+++ b/src/interface.ts
@@ -0,0 +1,53 @@
+export interface IBls {
+  PrivateKey: {
+    fromBytes(bytes: Uint8Array): IPrivateKey;
+    fromHex(hex: string): IPrivateKey;
+    fromKeygen(): IPrivateKey;
+  };
+  PublicKey: {
+    fromBytes(bytes: Uint8Array): IPublicKey;
+    fromHex(hex: string): IPublicKey;
+    aggregate(pubkeys: IPublicKey[]): IPublicKey;
+  };
+  Signature: {
+    fromBytes(bytes: Uint8Array): ISignature;
+    fromHex(hex: string): ISignature;
+    aggregate(signatures: ISignature[]): ISignature;
+  };
+
+  sign(secretKey: Uint8Array, messageHash: Uint8Array): Buffer;
+  aggregatePubkeys(publicKeys: Uint8Array[]): Buffer;
+  aggregateSignatures(signatures: Uint8Array[]): Buffer;
+  verify(publicKey: Uint8Array, messageHash: Uint8Array, signature: Uint8Array): boolean;
+  verifyAggregate(publicKeys: Uint8Array[], messageHash: Uint8Array, signature: Uint8Array): boolean;
+  verifyMultiple(publicKeys: Uint8Array[], messageHashes: Uint8Array[], signature: Uint8Array): boolean;
+
+  initBLS: () => Promise<void>;
+  destroy: () => void;
+}
+
+export interface IKeypair {
+  publicKey: IPublicKey;
+  privateKey: IPrivateKey;
+}
+
+export interface IPublicKey {
+  toBytes(): Buffer;
+  toHex(): string;
+}
+
+export interface ISignature {
+  toBytes(): Buffer;
+  toHex(): string;
+  verify(publicKey: IPublicKey, message: Uint8Array): boolean;
+  verifyAggregate(publicKeys: IPublicKey[], message: Uint8Array): boolean;
+  verifyMultiple(publicKeys: IPublicKey[], messages: Uint8Array[]): boolean;
+}
+
+export interface IPrivateKey {
+  value: any;
+  toPublicKey(): IPublicKey;
+  signMessage(message: Uint8Array): ISignature;
+  toBytes(): Buffer;
+  toHex(): string;
+}
diff --git a/test/switch.ts b/test/switch.ts
index 19765bb..4fb8799 100644
--- a/test/switch.ts
+++ b/test/switch.ts
@@ -1,11 +1,11 @@
 import blst from "../src/blst";
 import herumi from "../src/herumi";
+import {IBls} from "../src/interface";
 
 export type Implementation = "blst" | "herumi";
-export const implementations: Implementation[] = ["blst", "herumi"];
 
 // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-export function getBls(implementation: Implementation) {
+export function getBls(implementation: Implementation): IBls {
   switch (implementation) {
     case "blst":
       return blst;
@@ -15,17 +15,16 @@ export function getBls(implementation: Implementation) {
 }
 
 export function forEachImplementation(
+  implementations: Implementation[],
   callback: (bls: ReturnType<typeof getBls>, implementation: Implementation) => void
 ): void {
   for (const implementation of implementations) {
     describe(implementation, () => {
       const bls = getBls(implementation);
 
-      if (implementation === "herumi") {
-        before(async () => {
-          await bls.initBLS();
-        });
-      }
+      before(async () => {
+        await bls.initBLS();
+      });
 
       callback(bls, implementation);
     });
diff --git a/test/unit/index.test.ts b/test/unit/index.test.ts
index 4001b82..32da4a0 100644
--- a/test/unit/index.test.ts
+++ b/test/unit/index.test.ts
@@ -1,8 +1,8 @@
 import {expect} from "chai";
-import {forEachImplementation} from "../switch";
+import {IBls} from "../../src/interface";
 import {getN, randomMessage} from "../util";
 
-forEachImplementation((bls) => {
+export function runIndexTests(bls: IBls) {
   // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
   function getRandomData() {
     const sk = bls.PrivateKey.fromKeygen();
@@ -95,4 +95,4 @@ forEachImplementation((bls) => {
       expect(isValid).to.be.false;
     });
   });
-});
+}
diff --git a/test/unit/keypair.test.ts b/test/unit/keypair.test.ts
index 4884217..82b2deb 100644
--- a/test/unit/keypair.test.ts
+++ b/test/unit/keypair.test.ts
@@ -1,27 +1,27 @@
-import {expect} from "chai";
-import {forEachImplementation} from "../switch";
+// import {expect} from "chai";
+// import {IBls} from "../../src/interface";
 
-forEachImplementation((bls) => {
-  describe("Keypair", () => {
-    it("should create from private and public key", () => {
-      const sk = bls.PrivateKey.fromKeygen();
-      const sk2 = bls.PrivateKey.fromKeygen();
-      const pk = sk.toPublicKey();
+// export function runKeypairTests(bls: IBls) {
+//   describe("Keypair", () => {
+//     it("should create from private and public key", () => {
+//       const sk = bls.PrivateKey.fromKeygen();
+//       const sk2 = bls.PrivateKey.fromKeygen();
+//       const pk = sk.toPublicKey();
 
-      const keypair = new bls.Keypair(sk as any, pk as any);
+//       const keypair = new bls.Keypair(sk, pk);
 
-      expect(keypair.publicKey).to.be.equal(pk);
-      expect(keypair.privateKey).to.be.equal(sk);
-      expect(keypair.privateKey).to.not.be.equal(sk2);
-    });
+//       expect(keypair.publicKey).to.be.equal(pk);
+//       expect(keypair.privateKey).to.be.equal(sk);
+//       expect(keypair.privateKey).to.not.be.equal(sk2);
+//     });
 
-    it("should create from PrivateKey", () => {
-      const sk = bls.PrivateKey.fromKeygen();
-      const pk = sk.toPublicKey();
+//     it("should create from PrivateKey", () => {
+//       const sk = bls.PrivateKey.fromKeygen();
+//       const pk = sk.toPublicKey();
 
-      const keypair = new bls.Keypair(sk as any);
+//       const keypair = new bls.Keypair(sk as any);
 
-      expect(keypair.publicKey.toHex()).to.equal(pk.toHex());
-    });
-  });
-});
+//       expect(keypair.publicKey.toHex()).to.equal(pk.toHex());
+//     });
+//   });
+// }
diff --git a/test/unit/privateKey.test.ts b/test/unit/privateKey.test.ts
index f68cfb1..b849cf9 100644
--- a/test/unit/privateKey.test.ts
+++ b/test/unit/privateKey.test.ts
@@ -1,7 +1,7 @@
 import {expect} from "chai";
-import {forEachImplementation} from "../switch";
+import {IBls} from "../../src/interface";
 
-forEachImplementation((bls) => {
+export function runPrivateKeyTests(bls: IBls) {
   describe("PrivateKey", () => {
     it("should generate fromKeygen private key", () => {
       const privateKey1 = bls.PrivateKey.fromKeygen();
@@ -23,4 +23,4 @@ forEachImplementation((bls) => {
       expect(() => bls.PrivateKey.fromHex("0x2123")).to.throw();
     });
   });
-});
+}
diff --git a/test/unit/publicKey.test.ts b/test/unit/publicKey.test.ts
index 5ef7616..0c66cf1 100644
--- a/test/unit/publicKey.test.ts
+++ b/test/unit/publicKey.test.ts
@@ -1,7 +1,7 @@
 import {expect} from "chai";
-import {forEachImplementation} from "../switch";
+import {IBls} from "../../src/interface";
 
-forEachImplementation((bls) => {
+export function runPublicKeyTests(bls: IBls) {
   describe("PublicKey", () => {
     const publicKey =
       "0xb6f21199594b56d77670564bf422cb331d5281ca2c1f9a45588a56881d8287ef8619efa6456d6cd2ef61306aa5b21311";
@@ -18,4 +18,4 @@ forEachImplementation((bls) => {
       bls.PrivateKey.fromKeygen().toPublicKey();
     });
   });
-});
+}
diff --git a/test/unit/run-all-implementations.test.ts b/test/unit/run-all-implementations.test.ts
new file mode 100644
index 0000000..854d6e3
--- /dev/null
+++ b/test/unit/run-all-implementations.test.ts
@@ -0,0 +1,12 @@
+import {runPrivateKeyTests} from "./privateKey.test";
+import {runPublicKeyTests} from "./publicKey.test";
+// import {runKeypairTests} from "./keypair.test";
+import {runIndexTests} from "./index.test";
+import {forEachImplementation} from "../switch";
+
+forEachImplementation(["blst", "herumi"], (bls) => {
+  runPrivateKeyTests(bls);
+  runPublicKeyTests(bls);
+  // runKeypairTests(bls);
+  runIndexTests(bls);
+});
diff --git a/test/unit/run-web-implementation.test.ts b/test/unit/run-web-implementation.test.ts
new file mode 100644
index 0000000..ea06044
--- /dev/null
+++ b/test/unit/run-web-implementation.test.ts
@@ -0,0 +1,12 @@
+import {runPrivateKeyTests} from "./privateKey.test";
+import {runPublicKeyTests} from "./publicKey.test";
+// import {runKeypairTests} from "./keypair.test";
+import {runIndexTests} from "./index.test";
+import {forEachImplementation} from "../switch";
+
+forEachImplementation(["herumi"], (bls) => {
+  runPrivateKeyTests(bls);
+  runPublicKeyTests(bls);
+  // runKeypairTests(bls);
+  runIndexTests(bls);
+});