What was before A.P.I even existed?

Before APIs existed, software systems were monolithic, isolated islands that could not easily communicate with each other. If two different programs needed to share data, developers had to rely on physical media transfers, manual data reentry, or hardcoded tightly-coupled integrations.

Because the abstract concept of a local "Application Programming Interface" dates back to the 1940s and 50s, "life before APIs" is generally divided into two eras: the era before local computer libraries (1940s–1950s) and the era before modern web/network APIs (1960s–1990s).

The Pre-API Era: Connecting Isolated Mainframes (1940s–1950s) 

In the earliest days of computing, software was written as one massive block of code. To pass information between systems or reuse functionalities, programmers used the following physical and manual methods:

Punch Cards and Magnetic Tapes: Data from one computer was printed onto physical punch cards or saved to tape reels. A human operator would walk the physical media over to a second computer to load the data. 

Manual Re-entry: A clerk would look at a printed paper report from one system and type the information line-by-line into a completely different terminal. 

Hardwired Connections: Computers were physically connected via custom-built cables, requiring custom programming to decode the exact electrical and data formats being used. 

The Pre-Web API Era: Early Digital Integration (1960s–1990s)

As operating systems evolved, software programs could finally reside on the same machine or network. However, before the invention of the modern Web APIs we use today (like REST or JSON), companies relied on highly rigid, fragile workarounds to bridge separate applications:

Shared Memory Blocks: Programs on the same computer would dump raw data into a specific, shared sector of the system's RAM. Other programs would read directly from that sector at their own speed.

* File-Based Transfers (FTP & Batch Processing): One system would generate a massive text file (like a CSV) at the end of the day. It would then upload that file to an [FTP server](https://en.wikipedia.org/wiki/File_Transfer_Protocol), where a second system would download it hours later and run an [ETL (Extract, Transform, Load) process](https://en.wikipedia.org/wiki/Extract,_transform,_load) to swallow the data.

* Direct Database Access: External systems were given the literal password to a primary database. They would execute raw SQL commands straight into the tables. If the database schema changed by even one column, the external system instantly crashed.

* Remote Procedure Calls (RPC): In the 1980s and 90s, technologies like [CORBA](https://en.wikipedia.org/wiki/Common_Object_Request_Broker_Architecture) and early RPC styles allowed a program on one machine to trigger a function on another. However, they were notoriously complex, tightly coupled, and language-dependent.

* Screen Scraping: If an app needed data from a terminal system, it would simulate a human user by reading the raw text directly off the display interface to extract key metrics. [1, 3, 7, 13, 14, 15, 16] 

* 

## How Modern APIs Fixed This

Modern web APIs—which exploded in popularity around 2000 through pioneers like Salesforce and eBay—introduced a clean "waiter" model. Instead of giving outside programs access to the entire "kitchen" (the database or internal source code), an API acts as a secure window where you hand over a highly structured request and get back an exactly formatted response. [4, 12, 17, 18, 19, 20] 

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If you are researching a specific system, let me know:

* 

* Are you looking into how vintage mainframes handled data?

* Are you curious about pre-REST internet protocols like SOAP?

* Do you need assistance migrating a legacy system to modern APIs? [1, 11, 19, 21, 22] 

* 

I can provide technical architecture breakdowns for any of these eras.

[1] [https://www.linkedin.com](https://www.linkedin.com/pulse/evolution-apis-from-early-integrations-modern-security-tjk6e)

[2] [https://logicloom.in](https://logicloom.in/api-driven-development-the-past-present-future/)

[3] [https://hygraph.com](https://hygraph.com/blog/evolution-of-apis)

[4] [https://dev.to](https://dev.to/wycliffealphus/the-evolution-of-apis-1cb1)

[5] [https://traefik.io](https://traefik.io/blog/the-history-and-evolution-of-apis)

[6] [https://www.sensedia.com](https://www.sensedia.com/pillar/history-of-apis)

[7] [https://www.reddit.com](https://www.reddit.com/r/explainlikeimfive/comments/1cvl9ot/eli5_what_was_used_before_apis_became_the_standard/)

[8] [https://radiostud.io](https://radiostud.io/evolution-of-apis-past-present-and-future/)

[9] [https://www.linkedin.com](https://www.linkedin.com/pulse/why-i-how-feature-from-70-year-old-programming-todays-larry-povkovich)

[10] [https://en.wikipedia.org](https://en.wikipedia.org/wiki/API)

[11] [https://www.linkedin.com](https://www.linkedin.com/pulse/understanding-apis-history-importance-modern-ghurani-cert-cii)

[12] [https://aws.amazon.com](https://aws.amazon.com/what-is/api/)

[13] [https://medium.com](https://medium.com/@chandramanohar/evolution-of-application-integration-and-api-first-approach-15b35f4f305f)

[14] [https://increment.com](https://increment.com/apis/land-before-modern-apis/)

[15] [https://www.crmsoftwareblog.com](https://www.crmsoftwareblog.com/2021/10/software-integration-evolution-past-present-future/)

[16] [https://cashapona.com](https://cashapona.com/2023/10/10/evolution-of-application-integration-and-api-first-approach/)

[17] [https://blog.postman.com](https://blog.postman.com/intro-to-apis-history-of-apis/)

[18] [https://www.youtube.com](https://www.youtube.com/watch?v=bVlkA5W6gl8)

[19] [https://yusapi.com](https://yusapi.com/blog-english/the-history-of-apis-what-was-the-first-api/)

[20] [https://increment.com](https://increment.com/apis/land-before-modern-apis/)

https://you.com 

https://you.com/resources/the-history-of-apis

 https://www.blueprism.com

https://www.blueprism.com/resources/blog/ui-vs-api-automation/