diff --git a/bun.lockb b/bun.lockb
index a8b74b9..0695986 100755
Binary files a/bun.lockb and b/bun.lockb differ
diff --git a/src/fetch/openapi.ts b/src/fetch/openapi.ts
index 2b03bcd..dbdc721 100644
--- a/src/fetch/openapi.ts
+++ b/src/fetch/openapi.ts
@@ -14,7 +14,7 @@ const TAGS = {
   DOCS: "Documentation",
 } as const;
 
-export const chains = await supportedChainsQuery();
+const chains = await supportedChainsQuery();
 const block_example = (await makeQuery(await getBlock( new URLSearchParams({limit: "2"})))).data;
 
 const timestampSchema: SchemaObject = { anyOf: [
diff --git a/src/queries.spec.ts b/src/queries.spec.ts
index 7762f3f..5b55e0c 100644
--- a/src/queries.spec.ts
+++ b/src/queries.spec.ts
@@ -1,17 +1,26 @@
-import { expect, test } from "bun:test";
-import { getBlock, getChain } from "./queries.js";
-import { chains } from './fetch/openapi.js';
+import { expect, jest, mock, test } from "bun:test";
+import { createBlockQuery, getBlock, getChain } from "./queries.js";
+import { supportedChainsQuery } from "./fetch/chains.js";
 
-test("getBlock", () => {
-    expect(getBlock(new URLSearchParams({ chain: "eth", block_number: "123" })))
+// Mock supported chains data to prevent DB query
+mock.module("./fetch/chains.ts", () => ({ supportedChainsQuery: jest.fn().mockResolvedValue(["eth", "polygon"]) }));
+
+test("createBlockQuery", () => {
+    expect(createBlockQuery(new URLSearchParams({ chain: "eth", block_number: "123" })))
         .toBe(`SELECT * FROM blocks WHERE (chain == 'eth' AND block_number == '123') ORDER BY block_number DESC LIMIT 1`);
 
-    expect(getBlock(new URLSearchParams({ chain: "eth", greater_or_equals_by_timestamp: '1438270048', less_or_equals_by_timestamp: '1438270083', limit: '3' })))
+    expect(createBlockQuery(new URLSearchParams({ chain: "eth", greater_or_equals_by_timestamp: '1438270048', less_or_equals_by_timestamp: '1438270083', limit: '3' })))
         .toBe(`SELECT * FROM blocks WHERE (toUnixTimestamp(timestamp) >= 1438270048 AND toUnixTimestamp(timestamp) <= 1438270083 AND chain == 'eth') ORDER BY block_number DESC LIMIT 3`);
+});
+
+test("getBlock", async () => {
+    const singleChainQuery = new URLSearchParams({ chain: "eth", block_number: "123" });
+    expect(getBlock(singleChainQuery)).resolves.toBe(createBlockQuery(singleChainQuery));
 
-    // Check that if not chain parameter is passed, all chains are included in the selection
-    chains.forEach((chain) => {
-        expect(getBlock(new URLSearchParams({ block_number: "123" })))
+    // Check that if no chain parameter is passed, all chains are included in the selection
+    let supportedChains = await supportedChainsQuery();
+    supportedChains.forEach((chain) => {
+        expect(getBlock(new URLSearchParams({ block_number: "123" }))).resolves
         .toContain(`SELECT * FROM blocks WHERE (chain == '${chain}' AND block_number == '123') ORDER BY block_number DESC LIMIT 1`);
     });
 });
diff --git a/src/queries.ts b/src/queries.ts
index dcca57d..6393b06 100644
--- a/src/queries.ts
+++ b/src/queries.ts
@@ -1,6 +1,6 @@
-import { DEFAULT_SORT_BY, config } from './config.js';
+import { config } from './config.js';
 import { parseBlockId, parseBlockNumber, parseChain, parseLimit, parseSortBy, parseTimestamp } from './utils.js';
-import { chains } from './fetch/openapi.js';
+import { supportedChainsQuery } from './fetch/chains.js';
 
 export interface Block {
     block_number: number;
@@ -9,54 +9,54 @@ export interface Block {
     chain: string;
 }
 
-export function getBlock(searchParams: URLSearchParams) {
-    // TO-DO: Modulo block number (ex: search by every 1M blocks)
-
-    let createBlockQuery = (searchParams: URLSearchParams) => {
-        // SQL Query
-        let query = `SELECT * FROM ${config.table}`;
-        const where = [];
+export function createBlockQuery (searchParams: URLSearchParams) {
+    // SQL Query
+    let query = `SELECT * FROM ${config.table}`;
+    const where = [];
 
-        // Clickhouse Operators
-        // https://clickhouse.com/docs/en/sql-reference/operators
-        const operators = [
-            ["greater_or_equals", ">="],
-            ["greater", ">"],
-            ["less_or_equals", "<="],
-            ["less", "<"],
+    // TO-DO: Modulo block number (ex: search by every 1M blocks)
+    // Clickhouse Operators
+    // https://clickhouse.com/docs/en/sql-reference/operators
+    const operators = [
+        ["greater_or_equals", ">="],
+        ["greater", ">"],
+        ["less_or_equals", "<="],
+        ["less", "<"],
         ]
-        for ( const [key, operator] of operators ) {
-            const block_number = parseBlockNumber(searchParams.get(`${key}_by_block_number`));
-            const timestamp = parseTimestamp(searchParams.get(`${key}_by_timestamp`));
-            if (block_number) where.push(`block_number ${operator} ${block_number}`);
-            if (timestamp) where.push(`toUnixTimestamp(timestamp) ${operator} ${timestamp}`);
-        }
+    for ( const [key, operator] of operators ) {
+        const block_number = parseBlockNumber(searchParams.get(`${key}_by_block_number`));
+        const timestamp = parseTimestamp(searchParams.get(`${key}_by_timestamp`));
+        if (block_number) where.push(`block_number ${operator} ${block_number}`);
+        if (timestamp) where.push(`toUnixTimestamp(timestamp) ${operator} ${timestamp}`);
+    }
 
-        // equals
-        const chain = parseChain(searchParams.get("chain"));
-        const block_id = parseBlockId(searchParams.get("block_id"));
-        const block_number = parseBlockNumber(searchParams.get('block_number'));
-        const timestamp = parseTimestamp(searchParams.get('timestamp'));
-        if (chain) where.push(`chain == '${chain}'`);
-        if (block_id) where.push(`block_id == '${block_id}'`);
-        if (block_number) where.push(`block_number == '${block_number}'`);
-        if (timestamp) where.push(`toUnixTimestamp(timestamp) == ${timestamp}`);
+    // equals
+    const chain = parseChain(searchParams.get("chain"));
+    const block_id = parseBlockId(searchParams.get("block_id"));
+    const block_number = parseBlockNumber(searchParams.get('block_number'));
+    const timestamp = parseTimestamp(searchParams.get('timestamp'));
+    if (chain) where.push(`chain == '${chain}'`);
+    if (block_id) where.push(`block_id == '${block_id}'`);
+    if (block_number) where.push(`block_number == '${block_number}'`);
+    if (timestamp) where.push(`toUnixTimestamp(timestamp) == ${timestamp}`);
 
-        // Join WHERE statements with AND
-        if ( where.length ) query += ` WHERE (${where.join(' AND ')})`;
+    // Join WHERE statements with AND
+    if ( where.length ) query += ` WHERE (${where.join(' AND ')})`;
 
-        // Sort and Limit
-        const limit = parseLimit(searchParams.get("limit"));
-        const sort_by = parseSortBy(searchParams.get("sort_by"));
-        query += ` ORDER BY block_number ${sort_by}`
-        query += ` LIMIT ${limit}`
+    // Sort and Limit
+    const limit = parseLimit(searchParams.get("limit"));
+    const sort_by = parseSortBy(searchParams.get("sort_by"));
+    query += ` ORDER BY block_number ${sort_by}`
+    query += ` LIMIT ${limit}`
 
-        return query;
-    };
+    return query;
+};
 
+export async function getBlock(searchParams: URLSearchParams) {
     const chain = searchParams.get("chain");
 
     if (!chain) {
+        const chains = await supportedChainsQuery();
         let queries = chains.map((chain) => {
             searchParams.set('chain', chain);
             return createBlockQuery(searchParams);