diff --git a/contrib/Dockerfile b/contrib/Dockerfile
index 87eb3de3..6a5456b4 100644
--- a/contrib/Dockerfile
+++ b/contrib/Dockerfile
@@ -21,7 +21,9 @@ WORKDIR /srv/explorer/source
 SHELL ["/bin/bash", "-c"]
 
 RUN source /root/.nvm/nvm.sh \
- && npm install && (cd prerender-server && npm run dist) \
+ && npm install \
+ && npm test \
+ && (cd prerender-server && npm run dist) \
  && DEST=/srv/explorer/static/bitcoin-mainnet \
     npm run dist -- bitcoin-mainnet \
  && DEST=/srv/explorer/static/bitcoin-testnet \
diff --git a/package.json b/package.json
index 65925e7a..e90a926f 100644
--- a/package.json
+++ b/package.json
@@ -6,6 +6,7 @@
     "prerender-server": "cd prerender-server && npm start",
     "postinstall": "(cd client && npm install) && (cd prerender-server && npm install)",
     "dist": "./build.sh",
+    "test": "node --require @babel/register --test test/*.test.js",
     "l10n:fetch": "./lang/util/fetch-transifex.sh",
     "l10n:update-strings": "./lang/util/update-strings.sh"
   },
@@ -13,6 +14,7 @@
   "license": "MIT",
   "browserslist": "> 0.5%",
   "devDependencies": {
+    "@babel/register": "^7.12.10",
     "browserify-middleware": "^8.1.1",
     "express": "^4.17.1",
     "glob": "^7.1.6",
diff --git a/test/block-signatures.test.js b/test/block-signatures.test.js
new file mode 100644
index 00000000..c1f5ab84
--- /dev/null
+++ b/test/block-signatures.test.js
@@ -0,0 +1,52 @@
+const test = require("node:test");
+const assert = require("node:assert/strict");
+
+const { parseBlockSignatures } = require("../client/src/lib/block-signatures");
+
+test("parses a signblock witness", () => {
+  const block = {
+    ext: {
+      signblock_witness: [
+        [],
+        [0x01],
+        [0x02],
+        [0x52, 0x53, 0xae],
+      ],
+    },
+  };
+
+  assert.deepEqual(parseBlockSignatures(block), {
+    requiredSignatures: 2,
+    totalSigners: 3,
+    signatureCount: 2,
+    source: "signblock_witness",
+  });
+});
+
+test("parses a legacy block proof", () => {
+  const signature = `09${"00".repeat(9)}`;
+  const block = {
+    proof: {
+      challenge: "5253ae",
+      solution: `00${signature}${signature}`,
+    },
+  };
+
+  assert.deepEqual(parseBlockSignatures(block), {
+    requiredSignatures: 2,
+    totalSigners: 3,
+    signatureCount: 2,
+    source: "challenge",
+  });
+});
+
+test("returns source-tagged errors for malformed signature data", () => {
+  const result = parseBlockSignatures({
+    ext: {
+      signblock_witness: [[0x00], [0x51, 0x51, 0xae]],
+    },
+  });
+
+  assert.equal(result.error.source, "signblock_witness");
+  assert.match(result.error.message, /dummy must be empty/);
+});
diff --git a/test/deduce-blinded.test.js b/test/deduce-blinded.test.js
new file mode 100644
index 00000000..93c4354a
--- /dev/null
+++ b/test/deduce-blinded.test.js
@@ -0,0 +1,57 @@
+const test = require("node:test");
+const assert = require("node:assert/strict");
+
+const { deduceBlinded } = require("../client/src/lib/deduce-blinded");
+
+test("deduces a single blinded output", () => {
+  const tx = {
+    vin: [
+      { prevout: { asset: "asset-a", value: 7 } },
+      { prevout: { asset: "asset-a", value: 4 } },
+    ],
+    vout: [
+      { asset: "asset-a", value: 6 },
+      { asset: null, value: null },
+    ],
+  };
+
+  deduceBlinded(tx);
+
+  assert.deepEqual(tx.vout[1], { asset: "asset-a", value: 5 });
+
+  tx.vin[0].prevout.value = 100;
+  deduceBlinded(tx);
+  assert.deepEqual(tx.vout[1], { asset: "asset-a", value: 5 });
+});
+
+test("deduces a single blinded input using bigint amounts", () => {
+  const tx = {
+    vin: [
+      { prevout: { asset: null, value: null } },
+      { prevout: { asset: "asset-a", value: 3n } },
+    ],
+    vout: [{ asset: "asset-a", value: 8n }],
+  };
+
+  deduceBlinded(tx);
+
+  assert.deepEqual(tx.vin[0].prevout, {
+    asset: "asset-a",
+    value: 5n,
+  });
+});
+
+test("rejects inconsistent balances instead of guessing a blinded value", () => {
+  const tx = {
+    vin: [
+      { prevout: { asset: "asset-a", value: 10 } },
+      { prevout: { asset: "asset-b", value: 5 } },
+    ],
+    vout: [{ asset: null, value: null }],
+  };
+
+  assert.throws(
+    () => deduceBlinded(tx),
+    /unexpected remainder while deducing blinded tx/,
+  );
+});
diff --git a/test/fees.test.js b/test/fees.test.js
new file mode 100644
index 00000000..d4e66ca0
--- /dev/null
+++ b/test/fees.test.js
@@ -0,0 +1,36 @@
+const test = require("node:test");
+const assert = require("node:assert/strict");
+
+const {
+  feerateCutoff,
+  getConfEstimate,
+} = require("../client/src/lib/fees");
+
+test("calculates fee cutoff at block size boundaries", () => {
+  assert.equal(
+    feerateCutoff([
+      [10, 500000],
+      [5, 499999],
+    ]),
+    0,
+  );
+  assert.equal(
+    feerateCutoff([
+      [10, 500000],
+      [5, 500000],
+    ]),
+    10,
+  );
+  assert.equal(feerateCutoff([[10, 1000000]]), null);
+});
+
+test("selects a confirmation target by numeric order", () => {
+  const estimates = {
+    25: 1,
+    10: 5,
+    2: 10,
+  };
+
+  assert.equal(getConfEstimate(estimates, 6), "10");
+  assert.equal(getConfEstimate(estimates, 0.5), -1);
+});
diff --git a/test/privacy-analysis.test.js b/test/privacy-analysis.test.js
new file mode 100644
index 00000000..eaabe24c
--- /dev/null
+++ b/test/privacy-analysis.test.js
@@ -0,0 +1,52 @@
+const test = require("node:test");
+const assert = require("node:assert/strict");
+
+const getPrivacyAnalysis =
+  require("../client/src/lib/privacy-analysis").default;
+
+test("skips privacy analysis for coinbase transactions", () => {
+  const tx = {
+    vin: [{ is_coinbase: true }],
+    vout: [],
+  };
+
+  assert.deepEqual(getPrivacyAnalysis(tx), []);
+});
+
+test("detects equal-output coinjoins only with explicit amounts", () => {
+  const vin = [
+    {
+      prevout: {
+        value: 2000,
+        scriptpubkey: "input-a",
+        scriptpubkey_type: "v0_p2wpkh",
+      },
+    },
+    {
+      prevout: {
+        value: 2000,
+        scriptpubkey: "input-b",
+        scriptpubkey_type: "v0_p2wpkh",
+      },
+    },
+  ];
+  const vout = [1000, 1000, 900, 800].map((value, index) => ({
+    value,
+    scriptpubkey: `output-${index}`,
+    scriptpubkey_type: "v0_p2wpkh",
+  }));
+
+  assert.deepEqual(
+    getPrivacyAnalysis({ vin, vout }),
+    ["coinjoin-equal-outputs"],
+  );
+
+  const confidentialVin = [
+    { ...vin[0], prevout: { ...vin[0].prevout, value: null } },
+    vin[1],
+  ];
+  assert.deepEqual(
+    getPrivacyAnalysis({ vin: confidentialVin, vout }),
+    [],
+  );
+});