Fintech software development guides: market data, orders, payments and cost
For product teams adding market data, broker connections, order handling, payments or portfolio tracking to a finance product, including Turkish sources and rails.
Short answer: A fintech app is usually built from a few parts: a market data source with the right license, a broker or exchange connection, an order management layer, and reporting. Licensing and permissions often shape a project more than the code does, which is why these guides start with what you are allowed to build.
The page starts with what data you may use and on which terms, then covers broker connections and order handling, read-only portfolio tracking and what drives the budget.
Each guide names the official source for its claims and dates anything that can change. They are general information about software and data, not legal advice, and they do not recommend a vendor.
- Market data and licenses
- Brokers, orders and routing
- Payments
- Scoping a finance product
- Portfolio tracking and cost
- Choosing a partner
Market data and licenses
What a data API delivers, why free feeds are usually delayed, and how Turkish sources such as Borsa Istanbul, TEFAS, KAP and EVDS are accessed.
- Stock market data APIs: free tiers, licenses, how to chooseUpdated November 5, 2026 · 13 min readStock market data APIs explained: real-time, delayed and end-of-day data, exchange licenses for commercial use, consolidated feeds, adjustments and a checklist.
- Financial data API checklist: license, coverage, limitsNovember 6, 2026 · 13 min readHow to evaluate a financial data API before you commit: license for display and redistribution, delay, history, limits, SLA, plus a tested Python check.
- Borsa Istanbul API: market data access and licensingUpdated November 5, 2026 · 12 min readIs there a Borsa Istanbul API? How BIST market data reaches apps: licensed vendors, real-time vs delayed, Level 1 to Level 2+, non-display use and 2026 fees.
- TEFAS API, KAP API and EVDS: Turkish fund and macro dataUpdated November 5, 2026 · 11 min readIs there a TEFAS API? Official access to Turkish fund, KAP disclosure and central bank EVDS data: endpoints, API keys, terms of use and data-quality traps.
- TCMB API: exchange rates from today.xml and EVDS in PythonNovember 6, 2026 · 13 min readTCMB API guide: today.xml exchange rates with no key, a tested Python client, holiday gaps, unit traps, EVDS series codes and TÜİK's SDMX route.
- Crypto tick data API: free archives, sizes and licensesNovember 6, 2026 · 13 min readCrypto tick data: trades, aggTrades, quotes and depth, exchange archives and REST limits, tested checksum and gap checks, real file sizes, license limits.
- ClickHouse market data: tables, Kafka and measured testsNovember 6, 2026 · 13 min readClickHouse market data tables for trades, quotes, depth and candles, when Kafka earns its cost, and sizes and query times measured on 30 million trades.
Brokers, orders and routing
Connecting to a broker over REST or FIX, keeping order state in one place and sending an order to the right venue.
- Broker API integration: REST, WebSocket and FIXUpdated November 5, 2026 · 11 min readBroker API integration: REST and WebSocket vs FIX sessions, sequence numbers, execution reports, client order IDs, drop copies and certification tests.
- Crypto order management system: what an OMS actually doesNovember 5, 2026 · 13 min readCrypto order management system explained: order states, client order IDs, partial fills, reconciliation, pre-trade limits, exchange adapters and OMS vs EMS.
- Smart order routing in crypto: how routers pick venuesNovember 5, 2026 · 12 min readSmart order routing in crypto: merged depth, fee-adjusted price, balances per venue, partial fills, re-routing, Binance SOR and where regulation starts.
- Execution algorithms: VWAP, POV and arrival price mechanicsNovember 6, 2026 · 13 min readExecution algorithms for product leads: TWAP, VWAP, POV and arrival price mechanics, a tested VWAP simulation, native venue options, and build or use.
Payments
Payment gateways and instant payments in Turkey, and what the travel rule asks of crypto transfers.
- Turkey payment gateway: licenses, local cards and PayPalNovember 6, 2026 · 13 min readTurkey payment gateway rules from TCMB and BDDK texts: who may collect cards, how to read the register, foreign company limits, installments, PayPal and Stripe.
- iyzico API: sandbox, HMAC signing and webhooks in PythonNovember 6, 2026 · 13 min readiyzico API guide: sandbox keys, IYZWSv2 HMAC-SHA256 signing, X-IYZ-SIGNATURE-V3 webhooks, error 1000 causes and tested Python, from docs read 6 November 2026.
- PayTR API: iFrame token, callback and test mode in PythonNovember 6, 2026 · 13 min readPayTR API guide: exact iFrame token order, callback hash, repeated notifications, test mode, amount formats and official sample errors, with tested Python code.
- Param API integration: 3D Secure flow and 2026 statusNovember 6, 2026 · 13 min readParam API guide: TMSF trusteeship and TCMB register status read 6 November 2026, the archived 3D Secure flow, SHA1 callback check and tested Python.
- Fast payment system Turkey: FAST, TR Karekod, open bankingNovember 6, 2026 · 13 min readFast payment system Turkey map: FAST limit TRY 300,000 from 26 August 2026, TR Karekod rules, open banking API 2.0.1, who may connect and a tested QR parser.
- Travel rule API: IVMS 101 data, protocols and what to buildNovember 6, 2026 · 13 min readTravel rule API build guide: who is covered, IVMS 101 fields with a tested validator, protocols, unhosted wallets, message states, retries and storage.
Scoping a finance product
A finance product is shaped before any code is written: by who holds client money and the license, which data it may show, and which records it must keep and reconcile.
- Trading app development company: licenses, data, testingNovember 6, 2026 · 13 min readHiring a trading app development company? Who must hold the license, how orders reach a licensed broker, data rights, tests to demand and red flags.
- Wealth management software development: modules and risksNovember 6, 2026 · 13 min readWealth management software development, scoped: modules, custodian data, reconciliation, performance and fee tests, record rules and the advice line.
Portfolio tracking and cost
Read-only portfolio tracking built on exchange APIs, and what drives the build effort and the recurring bill of a finance app.
- Crypto portfolio tracker API: build on read-only keysNovember 5, 2026 · 12 min readCrypto portfolio tracker API guide: read-only keys, balances, fills and transfers endpoints, pagination, rate limits, an append-only ledger and average cost.
- Fintech app development cost: ranges, drivers, feesUpdated November 5, 2026 · 12 min readHow much does it cost to build a fintech app? Cost drivers, recurring data and platform fees, licensing questions, team roles, phases and comparable estimates.
Choosing a partner
What to require when you outsource, and how to verify a partner in Turkey.
- Outsource software development compliance: clause checklistNovember 6, 2026 · 13 min readOutsourcing regulated software work? Map each clause to GDPR Art. 28, DORA Art. 30, FCA, KVKK and TCMB texts, with the evidence to ask a Turkish partner for.
- Software development company in Turkey: how to verify oneNovember 6, 2026 · 13 min readHiring a software development company in Turkey? Verify the entity and signatory, take code rights in a valid written form, and settle VAT and data rules.
- Fintech companies in Turkey: licenses and how to check oneNovember 6, 2026 · 13 min readFintech companies in Turkey need a TCMB, BDDK or SPK license for regulated work. Register counts read 5 November 2026, partner rules and a check script.
From Fincode
- Market data API integration and pipelinesServiceMarket data API integration and pipelines: collectors, storage, backfill and gap reports for data you are licensed to use. Fincode sells software, not data.
- Fintech software partner in Turkey: start with what you can checkFincodeLooking for a software development company in Turkey? Check Fincode's registry facts and samples, and learn to verify any Turkish company in official registers.
- Fintech app development for iOS and webServiceFintech app development for iOS and web, from a written scope. Fiva, our own iPhone app in beta, is the one real example, and it places no trades.
- Trading bot dashboards and read-only reportingServiceTrading bot dashboards and read-only reporting across your own accounts: balances, fills, reconciliation and software health. No order button, no advice.
- Technical due diligence and product review for fintech projectsServiceTechnical due diligence for fintech projects: product, market, architecture, code and security review, with a prioritized findings report and a roadmap.
- Crypto exchange API integration servicesServiceConnect crypto exchange APIs to your app, bot or internal tool: market data, orders and balances, with rate-limit handling, retries, logs and documentation.
- Subcontract crypto API and trading software development for agenciesServiceExchange connectors, rule-based trading modules and TradingView bridges built as subcontract work for software agencies, with written scope and test reports.
- Broker API order management integration: example scenarioExample project scenarioExample scenario: connecting internal tools to a brokerage trading API with an order management layer, permissions, risk checks, audit trail and failover.
- Read-only crypto portfolio risk dashboard: example scenarioExample project scenarioExample scenario for one dashboard of balances, positions, P&L, exposure and liquidation distance across crypto exchanges, built on read-only API keys.
- KAP disclosure alert bot for Telegram: example scenarioExample project scenarioExample scenario: a bot that classifies and summarizes KAP disclosures for a watchlist and sends them to Telegram: data access, deduplication, monitoring.
Frequently asked questions
What is a fintech app?
Software that delivers a financial service or financial data to its users, such as payments, investing, market data or portfolio tracking. What it may do depends on the licenses and permissions behind it, so check those before you design the product.
Why are free stock market data APIs usually delayed?
What you may build with a data API depends on the exchange license behind it. Real-time display, non-display use by algorithms and redistribution are licensed and priced separately, so free APIs are usually delayed or limited to personal use.
These guides are general information about software and markets, not investment, legal or tax advice. Automated trading can lose money, past or backtested performance does not guarantee future results, and the rules that apply depend on your jurisdiction and your exchange's terms. For readers in Turkey, Article 99/A of Capital Markets Law No. 6362 treats activity by foreign crypto-asset platforms directed at Turkish residents as unauthorized.
Other guides
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