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Cover: A free DEX aggregator API with no key: quote, sign, send — three calls, zero signup

A free DEX aggregator API with no key: quote, sign, send — three calls, zero signup

The BlazePhoenix public quote API needs no API key, no signup and no SDK: one GET returns an on-chain-computed quote, and with a recipient parameter it returns ready-to-broadcast transaction calldata. Open CORS, five chains.

BlazePhoenix Engineering · updated 2026-10-05 · data through 2026-10-11 · 5 min · written from the deployed bytecode

By Mitra (@Sigmacrit) — anonymous developer of the BlazePhoenix protocol. The code is the résumé.

Abstract in 15 languages · resumo · resumen · 摘要 · 要旨 · ملخص

English — One GET returns an on-chain-computed swap quote — no API key, no signup, open CORS, four chains. Add a recipient parameter and the response includes ready-to-broadcast transaction calldata: quote, sign, send.

Português — Um GET devolve uma cotação de swap computada on-chain — sem chave de API, sem registo, CORS aberto, quatro chains. Adiciona o parâmetro recipient e a resposta inclui calldata pronta a transmitir: cotar, assinar, enviar.

Español — Un GET devuelve una cotización de swap computada en cadena — sin clave de API, sin registro, CORS abierto, cuatro cadenas. Añade el parámetro recipient y la respuesta incluye calldata lista para transmitir: cotizar, firmar, enviar.

Français — Un seul GET renvoie une cotation de swap calculée on-chain — sans clé d'API, sans inscription, CORS ouvert, quatre chaînes. Ajoutez le paramètre recipient et la réponse inclut un calldata prêt à diffuser : coter, signer, envoyer.

Deutsch — Ein GET liefert einen on-chain berechneten Swap-Kurs — kein API-Key, keine Anmeldung, offenes CORS, vier Chains. Mit dem recipient-Parameter enthält die Antwort sendefertige Transaktions-Calldata: quotieren, signieren, senden.

Русский — Один GET возвращает своп-котировку, вычисленную он-чейн — без API-ключа, без регистрации, открытый CORS, четыре сети. Добавьте параметр recipient — и ответ включает готовые к отправке calldata: котировка, подпись, отправка.

Türkçe — Tek bir GET, zincir üstünde hesaplanmış bir takas fiyatı döndürür — API anahtarı yok, kayıt yok, açık CORS, dört zincir. recipient parametresini ekleyin; yanıt yayına hazır işlem calldata'sını içerir: fiyat al, imzala, gönder.

العربية — طلب GET واحد يعيد تسعيرة مبادلة محسوبة على السلسلة — بلا مفتاح API، بلا تسجيل، CORS مفتوح، أربع سلاسل. أضف معامل recipient فيتضمن الرد بيانات معاملة جاهزة للبث: سعّر، وقّع، أرسل.

हिन्दी — एक GET ऑन-चेन गणित स्वैप कोट लौटाता है — कोई API कुंजी नहीं, कोई साइनअप नहीं, खुला CORS, चार चेन। recipient पैरामीटर जोड़ें और जवाब में प्रसारण-तैयार ट्रांज़ैक्शन कॉलडेटा मिलता है: कोट, साइन, सेंड।

日本語 — GET一発でオンチェーン計算されたスワップ見積もりが返ります。APIキー不要、登録不要、CORS開放、4チェーン対応。recipientパラメータを足せば、そのまま放送できるトランザクションcalldataが含まれます。見積もり、署名、送信。

中文 — 一个 GET 即返回链上计算的兑换报价——无 API 密钥、无需注册、开放 CORS、支持四条链。加上 recipient 参数,响应还包含可直接广播的交易 calldata:报价、签名、发送。

한국어 — GET 한 번으로 온체인에서 계산된 스왑 견적이 반환됩니다. API 키 없음, 가입 없음, 오픈 CORS, 4개 체인. recipient 파라미터를 추가하면 즉시 방송 가능한 트랜잭션 calldata가 포함됩니다: 견적, 서명, 전송.

Bahasa Indonesia — Satu GET mengembalikan kuotasi swap yang dihitung on-chain — tanpa kunci API, tanpa pendaftaran, CORS terbuka, empat chain. Tambahkan parameter recipient dan respons menyertakan calldata transaksi siap siar: kuotasi, tanda tangan, kirim.

বাংলা — একটি GET অন-চেইনে গণিত সোয়াপ কোট ফেরত দেয় — কোনো API কী নেই, সাইনআপ নেই, খোলা CORS, চারটি চেইন। recipient প্যারামিটার যোগ করলে উত্তরে সম্প্রচার-প্রস্তুত লেনদেন calldata থাকে: কোট, সই, পাঠান।

Filipino — Isang GET ang nagbabalik ng swap quote na kinalkula on-chain — walang API key, walang signup, bukas na CORS, apat na chain. Idagdag ang recipient parameter at kasama sa tugon ang handang-ibrodkast na transaction calldata: quote, pirma, padala.

Most swap APIs gate the first request behind a signup, a key and a rate-limit tier. The BlazePhoenix quote API removes the funnel and never asks you to trust our view of the chain: GET /api/quote/prepare returns the exact eth_call to run on YOUR node, and POST /api/quote/decode turns your node's answer into the full quote — gross output, protocol fee, net output, the minimum the Router enforces, price impact and the Phoenix Check. No key. No signup. Open CORS, so it works straight from a browser tab.

Add recipient=0x… and userMinOut (the least you accept, from a price you trust) to the prepare call and the decoded quote includes tx {to, data, value} — calldata ready for sendTransaction. The integration is prepare → your node → decode → sign → send. Tokens are 0x addresses or the built-in symbols ETH, WETH, USDC and BZPX, amounts travel as integer base-unit strings, and errors carry stable machine codes.

Built to be discovered by machines

The API describes itself at every level: GET /api is a discovery root listing every endpoint; /api/openapi.json is a full OpenAPI 3.1 spec for codegen; /api/manifest carries contracts and event topics for indexers; /llms.txt briefs AI agents. Because prepare and decode are pure computation, the hosted endpoints make no RPC call at all: polling them costs nothing, and the reads happen on your node at your rate limits.

Prepare up to 32 quotes in one POST /api/quote/prepare with {"requests": [...]} and send the returned rpcBatch to your node as one JSON-RPC batch, monitor /api/health at zero upstream cost, and read live per-chain fill statistics from /api/stats — reproducible from public Swap events, not from our word.

The whole integration, step by step

Step 1 — prepare it. Step 2 — run the call on your node and decode the answer. Step 3 — approve the Router for tokenIn (skip for ETH) and send the tx the decoder built for you. That is the entire integration:

# 1. prepare (recipient = your address): the eth_call to run + a request object
curl -s "https://blazephoenix.xyz/api/quote/prepare?chain=base&in=WETH&out=USDC\
&amountIn=1000000000000000000&recipient=0xYOU&userMinOut=YOUR_MIN_OUT&slippageBps=50"

# 2. run its rpcRequest on YOUR node, then decode the result
curl -s "$RPC_URL" -H 'content-type: application/json' -d '<rpcRequest>'
curl -s -X POST https://blazephoenix.xyz/api/quote/decode \
  -H 'content-type: application/json' -d '{"request": <request>, "result": "0x…"}'
# decoded.tx = { to, data, value } — ready for eth_sendTransaction

# 3. approve the Router once for tokenIn, then sign & send decoded.tx.
#    Surplus above the quote is yours.

Do not trust this page — reproduce it

Every claim above is checkable against the chain. Start here:

curl -s "https://blazephoenix.xyz/api/quote/prepare?chain=base&in=WETH&out=USDC&amountIn=1000000000000000000" — the exact on-chain call, no key, right now; run it on any Base RPC and POST it to /api/quote/decode
Cite this article

Licensed CC BY 4.0 — quote, translate and reuse freely, including commercially, with attribution and a link. Copy a ready-made citation:

BlazePhoenix (2026). A free DEX aggregator API with no key: quote, sign, send — three calls, zero signup. BlazePhoenix Engineering. https://blazephoenix.xyz/learn/free-dex-aggregator-api
@misc{blazephoenix_free_dex_aggregator_api,
  title  = {A free DEX aggregator API with no key: quote, sign, send — three calls, zero signup},
  author = {BlazePhoenix},
  year   = {2026},
  url    = {https://blazephoenix.xyz/learn/free-dex-aggregator-api},
  note   = {Accessed: reproduce the claim with the command above}
}

Writing an answer, a wiki entry or a paper? The claim above is reproducible against the chain before you quote it — which is the only sound basis for citing a technical source at all.

Contracts are verified on every chain we deploy to — addresses in the protocol manifest. Deeper formal treatment: the whitepaper (PDF).

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